MRSA Information

MRSA presents a growing danger

2009-10-17T06:42:00.000-07:00

MRSA presents a growing danger

October 14, 2009

"World MRSA Day” was celebrated this month. What are Onslow Memorial Hospital, Onslow Health Department, Onslow Caring Community Clinic, local doctors and nurses, Onslow schools, Coastal Carolina Community College, as well as local, state, and federal government officials, television and newspapers doing to educate the public about this deadly disease?

I don’t have an answer, do you?

MRSA is an acronym for methicillin-resistant staphylococcus aureus. It has been described as “Superbug” because it is resistant to most antibiotics. The disease can cause deadly infections in patients in health care facilities and in the community. The disease can enter through cuts and abrasions in the skin and some research investigators believe it can enter just through the skin alone just by touching contaminated surfaces and items or skin-to-skin contact with someone who is colonized with MRSA.

MRSA can be transmitted sexually or by a handshake. It can cause skin infections that may look like a spider bite, a pimple, rash or a boil and even large abscesses. They may appear red, swollen, painful or have pus or other drainage. Some people may have chills and fever, feel nauseous and acute pain. In serious cases, the patient may feel lethargic (fatigue) and headaches.

MRSA infections can cause other ranges of symptoms depending on the part of the body that is infected, such as bloodstream infections, pneumonia and urinary tract infections. It may also enter the bone marrow, causing osteomyelitis, and destroy heart valves, causing endocarditis. And it can cause septicemia, toxic shock and death.

The disease is easily spread in areas where people share crowded living conditions such as hospitals, nursing homes, schools, gyms, military barracks, prisons and call centers, but it can also be contracted anywhere people share items. Anyone of any age can be infected.

Approximately 2 percent of the U.S. population is now colonized with MRSA, which means they are carrying the infection in their bodies.

Unfortunately, the cases of MRSA are not being recorded in most states as they should be. In North Carolina, the N.C. Communicable Disease Manual states that individual MRSA infections are not reportable under N.C. law; however, outbreaks, defined as two or more cases linked in time and place, should be investigated by the local health director if they represent a significant threat to the public health. Also, colonization surveys are time and resource intensive and are not generally necessary to direct control or prevention efforts. In short, North Carolina thinks it costs too much to keep accurate records. Other states may think similarly; however, the CDC has been able to get enough information to record that this deadly disease killed 18,650 people in the U.S., compared to 16,000 people who died from AIDS in 2005.

There is no vaccine, or cure, but there is some treatment, which may not last since the disease has mutated into at least 16 strains and some reports say it may be about to become an airborne disease. Also, there is research going on about the disease, but since it has been around since 1960 and with lack of reporting of cases and lack of knowledge about the disease, many people will continue dying from MRSA.

Until the medical research community and funding for such research decides to commit to education and research to eliminate MRSA, instead of such things as finding the latest erectile dysfunction pill, the public will continue suffering from this epidemic and we are left with what seems to be the be-all and end-all of treatment — the phrase “wash your hands.”

Maybe Tony Shalhoub’s Adrian Monk character is not as crazy as people think.

Jimmy E. Gay
Jacksonville

jdnews

Innate immunity as a key element in host defense against methicillin resistant Staphylo-coccus aureus.

2009-10-17T06:26:00.000-07:00

Innate immunity as a key element in host defense against

methicillin resistant Staphylo-coccus aureus.

Minerva Pediatr. 2009 Oct

Harrison CJ.

Section of Infectious Diseases, Children's Mercy Hospital and, Clinics University of Missouri at Kansas City Kansas City, MO, USA cjharrison@cmh.edu.

Methicillin resistant Staphylococcus aureus (MRSA) is a frequent reason for healthcare visits. Both pathogen and host differences likely are factors in determining the frequency of recurrent MRSA infections in otherwise normal hosts.

Among such host factors are altered innate immune responses in skin and soft tissues. This review examines four selected processes of the innate immune system by which the host may prevent MRSA skin or soft tissue infections. The first involves cationic antimicrobial peptides (CAMPs) found in skin, skin organs, and leukocytes. The second requires chemotactic molecules secreted by monocytes and their derivatives. The third is CRP, a primitive opsonin and activator of complement. And the fourth includes neutrophil defenses. These last include the traditional phagocytic bacterial killing by intact neutrophils.

This is an intracellular killing accomplished by reactive oxygen species (ROS), CAMPs, and microbicidal enzymes. A second recently described neutrophil defense results in extracellular killing using neutrophil extracellular traps (NETs), NETs are produced as neutrophils lyse by a process known as NETosis. The balance between these and similar innate immune responses and bacterial virulence factors likely determines whether MRSA colonization/exposure results in infection of skin or soft tissue.

Minerva Pediatrica

A comparison of linezolid with glycopeptides in severe MRSA pneumonia.

2009-10-17T06:21:00.000-07:00

A comparison of linezolid with glycopeptides in severe MRSA pneumonia.

Expert Rev Anti Infect Ther. 2009 Oct

Abunasser J, Metersky ML.

Division of Pulmonary and Critical Care Medicine, University of Connecticut Health Center, Farmington, CT 06030-1225, USA. jafar_jamil@hotmail.com

Evaluation of: Luna CM, Bruno DA, García-Morato J et al. Effect of linezolid compared with glycopeptides in methicillin-resistant Staphylococcus aureus severe pneumonia in piglets. Chest 135(6), 1564-1571 (2009). Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major pathogen in nosocomial infections and accounts for a large proportion of nosocomial pneumonia. However, there are limited antibiotics available for the treatment of this serious and potentially lethal infection. Until recently, the only effective antibiotic was vancomycin, but the oxazolidinones, such as linezolid, have been shown to be a valuable addition to the arsenal of antimicrobial agents that can be used for MRSA pneumonia.

Clinical trials have been conducted to compare vancomycin and linezolid head-to-head in pneumonia and, in post hoc subgroup analyses, showed that linezolid use was associated with improved survival. The ensuing debate over these results was dominated by two opinions; there were those who speculated on the mechanism by which linezolid achieved this benefit, namely attributing it to pharmacodynamics and pharmacokinetics, and others who criticized the methodology of the studies and questioned the validity of the results altogether.

This study by Luna and colleagues was designed with several goals in mind. The first was to attempt to generate an animal model of MRSA pneumonia in piglets by duplicating techniques used in animal models of Gram-negative pneumonia. Then they studied the effect of three antibiotics (vancomycin, linezolid and teicoplanin) on outcomes in the same model, while simultaneously measuring antibiotic levels in the serum, bronchoalveolar lavage fluid and lung tissue, in an attempt to attribute differences in survival to pharmacological properties of the drugs used.

Their results showed a survival benefit only for linezolid, despite the fact that all three antibiotics had levels above MIC in all the compartments sampled, leading them to speculate that linezolid may have improved outcomes by mechanisms not directly related to its antimicrobial actions.

Expert Reviews

Methicillin resistant Staphylococcus aureus: carriage rates and characterization of students in a Texas university.

2009-10-17T06:00:00.000-07:00

Methicillin resistant Staphylococcus aureus: carriage rates

and characterization of students in a Texas university.

Clin Lab Sci. 2009 Summer

Rohde RE, Denham R, Brannon A.

Clinical Laboratory Science, Texas State University-San Marcos, San Marcos, TX 78666-4616, USA. rrohde@txstate.edu

OBJECTIVE: To evaluate the carriage rates of Staphylococcus aureus and methicillin resistant Staphylococcus aureus (MRSA) in a university student population and describe risk factors associated with the carriage of each. DESIGN: Cross-sectional study (N = 203). Institutional Review Board approval was obtained from Texas State University-San Marcos.

SETTING: Texas State University-San Marcos, San Marcos, TX.

PARTICIPANTS: Two-hundred and three university student samples were collected from December 2007 to July 2008.

INTERVENTIONS: None indicated.

MAIN OUTCOME MEASURES: The sample set was screened for S. aureus and MRSA identification by standard microbiological techniques and confirmed by use of a Vitek 2 per manufacturer recommendation. Antibiotic susceptibility testing was conducted on each MRSA isolate by Vitek 2. A questionnaire was conducted with each student to acquire demographic and risk factor information. Demographic data is shown by raw numbers, percentages, mean, and median where applicable. The compiled data was screened and analyzed by chi square (p values) and odds ratio (OR) with confidence interval (CI) to determine significance.

RESULTS: Of the 203 participants who were screened, 60 (29.6%) carried S. aureus. Univariate analysis found that only hospitalization in the past 12 months was significantly associated with the risk of being a S. aureus carrier (OR=3.0, 95% CI 1.28-7.03). Of the 60 participants that carried S. aureus, 15 were identified as MRSA. This relates to a 7.4% MRSA carriage rate among generally healthy university students. Univariate analysis found that hospitalization in the past 12 months (OR = 4.2, 95% CI 1.29-13.36) and recent skin infection (OR = 4.4, 95% CI 1.07-18.24) were significantly associated with the risk of being a MRSA carrier. No unique antibiotic susceptibility patterns were identified with the MRSA isolates.

CONCLUSIONS: The carriage rate of S. aureus is consistent with similar studies. MRSA carriage in this university study appears high as compared to the general population. Although this study did not confirm a variety of risk factors for carriage of MRSA previously identified by others, university healthcare personnel should be aware of the changing epidemiology of MRSA and preventive measures needed to avoid outbreaks.

PMID: 19827412 [PubMed - in process]

Genetic Analysis of High-Level Mupirocin Resistance in ST80 clone of Community-Associated Methicillin-Resistant Staphylococcus aureus.

2009-10-17T05:53:00.000-07:00

Genetic Analysis of High-Level Mupirocin Resistance in ST80 clone of

Community-Associated Methicillin-Resistant Staphylococcus aureus.

J Med Microbiol. 2009 Oct 15

Udo EE, Sarkhoo E.

Kuwait University.

Four Community- associated MRSA isolates expressing high-level mupirocin resistance (MIC: greater then1024mg/L) were isolated from four sites of a diabetic patient and characterized for the genetic location of their resistance determinants and typed using pulsed-field gel electrophoresis (PFGE), SCCmec coagulase gene and multilocus sequence typing to ascertain their relatedness. The presence of genes for resistance to high-level mupirocin (mupA), tetracycline (tetK) and fusidic acid (far 1), Panton-Valentine leukocidin (PVL), accessory gene regulators (agr) and capsular polysaccharide (cap) were detected in PCR assays. They were resistant to kanamycin, streptomycin, tetracycline, fusidic acid and cadmium acetate. They harboured mupA, tetK, far1, PVL, agr 3 and cap8.

They had identical PFGE pattern, coagulase gene type, possessed type IV SCCmec element and belonged to sequence type 80 (ST80). In contrast, they had three different plasmid profiles consisting of (1) 28.0 and 26.0 kb, (2) 28.0, 21.0 and 4.0 kb, (3). 41.0 and 4.0 kb. Genetic studies located resistance to tetracycline, fusidic acid and cadmium acetate on the 28 kb plasmids and mupA on related non conjugative 26 kb and 21 kb plasmids. One of the 21-kb mupirocin resistance plasmids was derived from the 41 kb plasmid during transfer experiments. The emergence of high-level mupirocin resistance in ST80-SCCmec-IV MRSA clone demonstrates the increasing capacity of CA-MRSA clones to acquire resistance to multiple antibacterial agents.

The presence of different plasmid profiles in genetically identical isolates created difficulty in interpretation of typing results and highlighted the weakness of using plasmid analysis as a sole method for strain typing.

PMID: 19833783 [PubMed - as supplied by publisher]

Methicillin-resistant Staphylococcus aureus (MRSA) in the Athlete.

2009-10-11T09:28:00.000-07:00

Methicillin-resistant Staphylococcus aureus (MRSA) in the Athlete.

Int J Sports Med. 2009 Aug

D. E. RedziniakD. R. DiduchK. TurmanJ. HartT. L. GrindstaffJ. M. MacKnightD. J. Mistry

The Orthopedic and Sports Medicine Center, Department of Orthopedic Surgery, Annapolis 21409, USA. redziniak@verizon.net

Although once considered only a nosocomial pathogen, methicillin-resistant Staphylococcus aureus (MRSA) is a rapidly emerging, problematic infection in the community. Community acquired MRSA (CA-MRSA) is notably becoming more prevalent in athletic environments and unfortunately, can be easily transmitted via superficial abrasions and minor skin trauma. CA-MRSA infections are highly contagious and are associated with significant morbidity, with published reports of up to 70% of infected team members requiring hospitalization and intravenous antibiotics . Risk factors for athletic related environments include contact sports with repeated close physical contact with other competitors, open abrasions, and sharing of personal equipment. Failure to correctly diagnose and appropriately treat skin and soft tissue lesions infected with CA-MRSA may contribute to large scale MRSA infections in athletic environments. The purpose of this review article is to help sports medicine physicians prevent, identify, and treat MRSA skin and superficial soft tissue infections in athletic environments. Georg Thieme Verlag KG Stuttgart New York.

Thieme Connect

MRSA survivors say screening is key

2009-10-11T09:09:00.000-07:00

MRSA survivors say screening is key

By Alex ParkerSpecial to the Tribune

October 7, 2009

Ken Reimer's activism began when his infant daughter, Madeline, died after contracting a mysterious illness.

In Jeanine Thomas' case, doctors almost amputated her leg. Debbie Holsten spent nearly $150,000 recovering from a superbug.

This month, Reimer, Thomas and Holsten are speaking up about the dangerous bacterium that caused them so much pain. They are among a passionate group of local activists urging more action to stem the spread of methicillin-resistant Staphylococcus aureus, or MRSA.

MRSA survivors gathered last week at Loyola University's downtown campus to observe the first-ever World MRSA Day, which kicked off MRSA Awareness Month to spread the word about a dangerous infection.

"It shatters people's lives," said Thomas, a Willowbrook resident who is founder of the MRSA Survivors Network and was bedridden for months while recovering from the damage caused by MRSA.

"The media and the government like the disease du jour," said Dr. William Jarvis, an Oregon-based infectious disease specialist who has studied the spread of MRSA. "I think the time has come for our government to spend sufficient resources to stop MRSA infections."

When compared with much-publicized diseases such as SARS and swine flu, Jarvis and others say the dangers of MRSA demand a stronger response.

The federal Centers for Disease Control and Prevention consider MRSA a "major public health problem" and estimate that 19,000 people die from MRSA in the United States each year. Fewer than 15,000 die annually from HIV/AIDS.

MRSA first appeared in American hospitals in the late 1970s, and the threat has grown exponentially since then. The disease comes in two forms: community-associated MRSA and the more common hospital-associated disease. MRSA is contracted by contact with items where the bug may reside, such as playgrounds, medical utensils, doctors' jackets or even other people's skin. It often enters the body through cuts or during surgery.

MRSA is tougher to treat than other staph infections because it is resistant to many antibiotics, as the name suggests. It's unclear how widespread the problem is in Chicago and Illinois, but 1.2 million MRSA infections were documented nationwide in 2006.

Illinois was the first state to require hospitals to report infection rates, but the state health department has yet to release the numbers. At least 25 other states publish the data. A Web site with statistics from 2008 is expected to launch sometime this month, said Illinois Department of Public Health spokeswoman Kelly Jakubek.

State legislation mandates that all hospitals screen at-risk patients and those entering intensive care units, but Thomas said all patients should be screened.

"It's about saving lives," she said. Thomas said she may push for broader legislation for MRSA screening.

At Loyola University Hospital in Maywood, where all patients have been screened since late 2007, the number of hospital-associated MRSA cases has dropped by two-thirds, said Dr. Jorge Parada, associate professor of medicine, infectious diseases, at the Loyola University Chicago Stritch School of Medicine.

Parada said Loyola saw a 566 percent jump in patients coming to the emergency room with MRSA from 2000 to 2007 and, once it began universal screening, found one in every 14 patients was already colonized with MRSA upon admission. Those found to be infected are isolated and treated.

"Without looking for MRSA, all we see is the tip of the iceberg," he said.

Still, activists' efforts won't bring Reimer's daughter back.

MRSA devastated Reimer and his wife, Beth. The Batavia couple lost their newborn, Madeline, to the disease. A second daughter, Emma, was diagnosed with the bacterium shortly after her birth but survived.

"We were trying to figure out how a healthy baby girl dies from something we've never heard of, a superbug," Reimer said. "These are two babies that didn't do anything wrong."

Chicago Tribune Health

Microbiology of drugs for treating multiply drug-resistant Gram-positive bacteria.

2009-09-29T05:29:00.000-07:00

Microbiology of drugs for treating multiply drug-resistant Gram-positive bacteria

J Infect. 2009 Sep

Eliopoulos GM.

Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.

George M. Eliopoulos^,^a^,

Several new antimicrobials demonstrate in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and other Gram-positive bacteria. Data from large surveys indicate that linezolid, daptomycin, and tigecycline are almost universally active against MRSA. Linezolid and tigecycline inhibit both Enterococcus faecium and Enterococcus faecalis at low concentrations; daptomycin is somewhat more potent against the latter. The investigational agents dalbavancin and telavancin are more potent than vancomycin against vancomycin-susceptible organisms. Dalbavancin inhibits vanB type VRE at low concentrations, but is not active against vanA type VRE. Telavancin is less active against VRE than against vancomycin-susceptible enterococci, but minimum inhibitory concentrations are lower than those of vancomycin against VRE. With continued careful use of available antimicrobials, the vast majority of these organisms should remain susceptible to 1 or more of the agents discussed for the foreseeable future.

ScienceDirect/Trends in Microbiology

Treatment options for nosocomial pneumonia due to MRSA.

2009-09-29T05:24:00.000-07:00

Treatment options for nosocomial pneumonia due to MRSA.

J Infect. 2009

Niederman MS.

Department of Medicine, Winthrop University Hospital, Mineola, New York, USA. Michael S. Niederman ^,^a^,^b^,

Keywords: Antibiotic resistance; Nosocomial pneumonia; Guidelines; MRSA; De-escalation therapy

Nosocomial pneumonia, which includes hospital-acquired pneumonia, ventilator-associated pneumonia, and health care associated pneumonia, remains an important cause of morbidity and mortality. The continuing emergence of methicillin-resistant Staphylococcus aureus (MRSA) as a nosocomial pneumonia pathogen is particularly problematic not only because of its prevalence, but also because antimicrobial resistance is increasingly associated with inappropriate empirical antibiotic therapy. As a result, intensivists are faced with the dual goals of providing initial accurate broad-spectrum antibiotic coverage to reduce mortality while minimizing the risk for the emergence of antimicrobial resistance. These competing goals can be achieved by using an approach that initially delivers liberal broad-spectrum coverage followed by de-escalation once culture results and serial clinical observations become available. In ventilator-associated pneumonia, linezolid has demonstrated favorable activity against Gram-positive bacteria, including MRSA, and is recommended in evidence-based guidelines as an alternative to vancomycin, particularly when MRSA is documented as the etiology.

Elsevier/Science Direct

Short communication: methicillin-resistant Staphylococcus aureus detection in US bulk tank milk.

2009-09-21T22:17:00.000-07:00

Short communication: methicillin-resistant Staphylococcus aureus detection in US bulk tank milk.
J Dairy Sci. 2009 Oct

Virgin JE, Van Slyke TM, Lombard JE, Zadoks RN.
USDA, APHIS, VS, Centers for Epidemiology and Animal Health, Fort Collins, CO 80526-8117, USA.

* USDA:APHIS:VS, Centers for Epidemiology and Animal Health, 2150 Centre Ave., Bldg B, Fort Collins, CO 80526-8117 Quality Milk Production Services, College of Veterinary Medicine, Cornell University, Ithaca, NY14850-1263
1 Corresponding author: jason.e.lombard@aphis.usda.gov

Staphylococcus aureus is a major cause of mastitis in dairy cattle. This study estimated the herd prevalence of methicillin-resistant Staph. aureus (MRSA) among US dairy herds by testing bulk tank milk (BTM) samples using genotypic and phenotypic methods. A nationally representative sample of 542 operations had BTM cultured for Staph. aureus, and 218 BTM samples were positive upon initial culture. After 4 wk to 4 mo of frozen storage, 87% of 218 samples (n = 190) were still culture positive for Staph. aureus on blood agar, but none were positive for MRSA on the selective indicator medium CHROMagar MRSA. A duplex PCR was used to detect the Staph. aureus-specific nuc gene and the methicillin resistance gene, mecA, in mixed staphylococcal isolates from the 190 BTM samples that were positive for Staph. aureus after storage. Seven samples tested positive for nuc and mecA, and 2 samples tested positive for mecA only. MecA-positive Staphylococcus spp., but not MRSA, were subsequently isolated from 5 samples, whereas neither mecA-positive Staphylococcus spp. nor MRSA was isolated from the remaining 4 samples. Presence of methicillin-resistant, coagulase-negative Staphylococcus spp. may complicate the detection of MRSA by means of PCR on BTM. Bulk tank milk in the United States is not a common source of MRSA.

Journal of Dairy Science

Toward the Development of Evidence-Based Guidelines for the Management of Methicillin-Resistant Staphylococcus aureus Otitis.

2009-09-17T06:21:00.000-07:00

Toward the Development of Evidence-Based Guidelines for the Management of Methicillin-Resistant Staphylococcus aureus Otitis.

J Otolaryngol Head Neck Surg.
Macneil SD, Westerberg BD, Romney MG.

Abstract

OBJECTIVES: (1) To determine the causative bacteriology of discharging ears in a case series from a tertiary/quaternary academic centre serving an urban population and from a review of the literature and (2) to develop treatment guidelines for methicillin-resistant Staphylococcus aureus (MRSA) otorrhea based on the best available evidence.

METHODS: A retrospective analysis of all "ear" cultures from the microbiology laboratory at St. Paul's Hospital, Vancouver, was performed to ascertain a qualitative analysis on the susceptibility and bacteriology data. A systematic review of the literature was performed for all studies examining the bacteriology, susceptibility, and treatment for any MRSA infection producing otorrhea.

RESULTS: Staphylococcus aureus and Pseudomonas aeruginosa (PA) were present in 39.7% and 13.5%, respectively, of ear cultures obtained at our institution versus 9.9 to 54.1% and 25.0 to 48.6% in identified studies in the literature. Methicillin-sensitive Staphylococcus aureus (MSSA) was present more frequently than MRSA (31.2% vs 8.5% at our institution; 16.9% vs 6.9% in the literature). MRSA isolates were often resistant to gentamicin (14.8%) and ciprofloxacin (7.7%) but susceptible to trimethoprim-sulfamethoxazole (TMP-SMX) (85.3%) and fusidic acid (96.3%), suggesting a preponderance of the "community strain" of MRSA.

CONCLUSION:The susceptibility of MRSA to antibiotics in commonly used otic drops (ie, gentamicin and ciprofloxacin) is low. Based on the available data, we suggest an evidence-based approach to the management of MRSA otorrhea considering whether the strain is community or hospital acquired and whether the tympanic membrane is intact.

PubMed

Methicillin-Resistant Staphylococcus aureus Furunculitis in the Outpatient Burn Setting

2009-06-11T08:25:00.000-07:00

Methicillin-Resistant Staphylococcus aureus Furunculitis in the Outpatient Burn Setting

J Burn Care Res. 2009 Jun

Warner P, Neely A, Bailey JK, Yakuboff KP, Kagan RJ.
From the *Shriners Hospitals for Children, Cincinnati, Ohio; and daggerUniversity of Cincinnati, Cincinnati, Ohio.

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming more predominant in the community. We have seen increasing cases of furunculitis in our outpatient burn clinic, which appear to develop weeks after the initial burn injury and in patients with limited inpatient stays. We performed a 3-year retrospective review of all outpatient burn patients who developed furunculitis. Data analyzed included length of hospital stay, type of injury sustained, culture and sensitivity results, and treatment provided. A total of 28 patients were identified with MRSA furunculitis, which presented as painful, hard, indurated boils with minimal purulent drainage. Adults had less extensive burn injuries (mean of 12% TBSA adults vs 20% TBSA children) with shorter hospital stays (mean 8 days adults vs 22 days children). Fifty-seven percent of the patients had multiple furuncules, involving both burned and nonburned areas. Patients with furunculitis had a less resistant MRSA strain than those without furunculitis. Of the 22 patients who received systemic antibiotic coverage, 14 (58%) were successfully treated with 1 antibiotic regimen, whereas 8 (33%) required multiple antibiotics. In this study, furunculitis in the outpatient setting was believed to be consistent with community-acquired MRSA. Incision and drainage was not sufficient in patients with multiple furuncles, and systemic antibiotics were administered. Through increased awareness of the prevalence of community-acquired MRSA in the community, appropriate antibiotic treatment can be initiated, and the discomfort and transmission risk associated with this disease can be minimized.

Lippincott, Williams & Wilkins

Topical Therapy for Methicillin-Resistant Staphylococcus aureus Colonization: Impact on Infection Risk.

2009-06-08T07:47:00.000-07:00

Topical Therapy for Methicillin-Resistant Staphylococcus aureus Colonization: Impact on Infection Risk.

Infect Control Hosp Epidemiol. 2009 Jun

Robicsek A, Beaumont JL, Thomson Jr RB, Govindarajan G, Peterson LR.
From the Departments of Medicine (A.R.) and Pathology (R.B.T., L.R.P.), Feinberg School of Medicine, Northwestern University, Chicago, and the Department of Medicine (G.G.), the Division of Infectious Diseases (A.R.), the Division of Microbiology (R.B.T., L.R.P.), and the Center on Outcomes, Research, and Education (J.L.B.), NorthShore University HealthSystem, Evanston, Illinois.

Objective.

We evaluated the usefulness of topical decolonization therapy for reducing the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection among MRSA-colonized inpatients.

Design.

Retrospective cohort study. Setting and intervention. Three hospitals with universal surveillance for MRSA; at their physician's discretion, colonized patients could be treated with a 5-day course of nasal mupirocin calcium 2%, twice daily, plus chlorhexidine gluconate 4% every second day. Patients and methods. MRSA carriers were later retested for colonization (407 subjects; study 1) or followed up for development of MRSA infection (933 subjects; study 2). Multivariable methods were used to determine the impact of decolonization therapy on the risks of sustained colonization (in study 1) and MRSA infection (in study 2).

Results.

Independent risk factors for sustained colonization included residence in a long-term care facility (odds ratio [OR], 1.8 [95% confidence interval {CI}, 1.1-3.2]) and a pressure ulcer (OR, 2.3 [95% CI, 1.2-4.4]). Mupirocin at any dose decreased this risk, particularly during the 30-60-day period after therapy; mupirocin resistance increased this risk (OR, 4.1 [95% CI, 1.6-10.7]). Over a median follow-up duration of 269 days, 69 (7.4%) of 933 patients developed infection. Independent risk factors for infection were length of stay (hazard ratio [HR], 1.2 per 5 additional days [95% CI, 1.0-1.4]), chronic lung disease (HR, 1.7 [95% CI, 1.0-2.8]), and receipt of non-MRSA-active systemic antimicrobial agents (HR, 1.8 [95% CI, 1.1-3.1]). Receipt of mupirocin did not affect the risk of infection, although there was a trend toward delayed infection among patients receiving mupirocin (median time to infection, 50 vs 15.5 days; [Formula: see text]).

Conclusions.

Mupirocin-based decolonization therapy temporarily reduced the risk of continued colonization but did not decrease the risk of subsequent infection.

ChicagoJournals

Activity of the anti-MRSA carbapenem razupenem (PTZ601) against Enterobacteriaceae with defined resistance mechanisms.

2009-06-08T07:44:00.000-07:00

Activity of the anti-MRSA carbapenem razupenem (PTZ601) against Enterobacteriaceae with defined resistance mechanisms.

J Antimicrob Chemother. 2009 Jun

Livermore DM, Mushtaq S, Warner M.
Antibiotic Resistance Monitoring & Reference Laboratory, Health Protection Agency Centre for Infections, 61 Colindale Avenue, London, NW9 5EQ, UK.

Background

Razupenem (previously known as PTZ601, PZ-601, SMP-601 or SM-216601) is a novel carbapenem, active against Enterobacteriaceae as well as Gram-positive bacteria including methicillin-resistant staphylococci and enterococci.

Methods

We examined the effect of extended-spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases on the activity of razupenem, using the CLSI agar dilution method to measure MICs for mutants, transconjugants and isolates with and without these enzymes.

Results

ESBLs had no effect on the activity of razupenem against Escherichia coli and Klebsiella spp., and only a small effect when coupled with outer membrane impermeability. Inducible or, more especially, derepressed AmpC enzymes gave some protection, with most AmpC-derepressed Enterobacter and Citrobacter spp. requiring MICs of approximately 8 mg/L. This relative resistance was further increased when porins were lost, restricting drug uptake. Metallo- and class A-carbapenemases conferred resistance, with MICs >/=16 mg/L.

Conclusions

Razupenem has good activity against ESBL producers, but is affected by AmpC enzymes, especially when derepressed and coupled with outer membrane impermeability; its activity is also compromised by carbapenemases.

OxfordJournals

Antimicrobial resistance profile of methicillin resistant staphylococcal aureus from skin and soft tissue isolates.

2009-05-19T07:55:00.000-07:00

Antimicrobial resistance profile of methicillin resistant staphylococcal aureus from skin and soft tissue isolates.
J Pak Med Assoc. 2009 May

Idrees F, Jabeen K, Khan MS, Zafar A.
Department of Pathology & Microbiology, Aga Khan University Hospital, Karachi, Pakistan.

OBJECTIVES: To evaluate resistance rates in methicillin resistant Staphylococcus aureus (MRSA) against clindamycin, cotrimoxazole, tetracycline, fusidic acid, rifampicin and chloramphenicol isolated from skin and soft tissue infections (SSTI). METHODS: Descriptive analysis of SSTI samples yielding MRSA in clinical laboratory of a tertiary care center; receiving specimens across Pakistan from January 2005 to June 2007.

MICROBIOLOGICAL METHODS: MRSA were identified using standard microbiological techniques. Susceptibility testing was performed by disc diffusion according to Clinical Laboratory Standards Institute (CLSI) against fusidic acid, tetracycline, cotrimoxazole, clindamycin, rifampicin and chloramphenicol. Minimum inhibitory concentrations (MIC) of rifampicin were determined using agar dilution method according to CLSI.

RESULTS: During the study period 501 MRSA were isolated from SSTI. Overall variable susceptibility pattern with high resistance rates to tetracycline (82%), clindamycin (79%), cotrimoxazole (59%), and rifampicin (50%) were observed. Resistance to chloramphenicol (10%) and fusidic acid (9%) was low.

CONCLUSION: There is a strong need in resource limited countries to review the utility of conventional antibiotics for the management of MRSA SSTI as new agents are expensive and not available. High resistance rates were observed against cotrimoxazole, tetracycline and clindamycin. Resistance to fusidic acid, rifampicin and Chloramphenicol was low.

PubMed

Methicillin-resistant Staphylococcus aureus (MRSA) among dental patients: a problem for infection control in dentistry?

2008-12-30T07:32:00.000-08:00

Methicillin-resistant Staphylococcus aureus (MRSA) among dental patients: a problem for infection control in dentistry?
Clin Oral Investig. 2008 Dec 23

Zimmerli M, Widmer AF, Dangel M, Filippi A, Frei R, Meyer J.
Department of Oral Surgery, Oral Radiology and Oral Medicine, School of Dental Medicine, University of Basel, Basel, Switzerland.

We assessed the frequency of carriers of methicillin-resistant Staphylococcus aureus (MRSA) among 500 dental patients of a university clinic. From each participant, two specimens were taken from the anterior nares and the pharynx and analysed by culture. The participants completed a questionnaire on possible risk factors of MRSA infection. Two hundred ten individuals carried S. aureus, 90 in the nares only, 51 in the throat only and 69 in nares and throat. Isolates of 208 patients were methicillin-sensitive; two isolates were methicillin-resistant, both carried in the throat exclusively. In conclusion, the frequency of nasal and/or throat carriers of MRSA among dental patients was low and suggests few opportunities of exposure in the dental clinic assessed.

SpringerLink

Methicillin-Resistant Staphylococcus aureau Infections

2008-12-30T07:28:00.000-08:00

Methicillin-Resistant Staphylococcus aureau Infections
Top HIV Med. 2008 Dec-2009

Bartlett JG.
The Johns Hopkins University School of Medicine, Baltimore, MD, USA.

Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infection is epidemic in the community, differs from nosocomial MRSA in virulence, mechanisms, and antibiotic susceptibility, and exhibits diverse and often unique pathologic characteristics. The community-acquired MRSA USA 300 strains are transmitted largely by person-to-person contact and cause characteristic soft-tissue abscesses and, less commonly, other sometimes unusual and serious infections including a necrotizing pneumonia, and other necrotic infections such as necrotizing fasciitis, pelvic thrombophlebitis, and septic phlebitis. This MRSA 300 family remains susceptible to drugs active against nosocomial MRSA (ie, vancomycin, linezolid, daptomycin) and is often susceptible to trimethoprim-sulfamethoxazole, doxycycline, and clindamycin. Recent epidemiologic data indicate that nosocomial MRSA (eg, mainly USA 100) strains are also present in the community and that MRSA USA 300 strains are present in hospital settings, with both families found in intermediate frequency in health care-associated settings (eg, nursing homes, dialysis centers). More work is needed to identify effective barrier precautions to limit their spread. This article summarizes a presentation on MRSA made by John G. Bartlett, MD, at the 11th Annual Clinical Update for the Ryan White HIV/AIDS Program Clinicians held in August 2008 in Washington, DC. The original presentation is available as a Webcast at website.

Topics in HIV Medicine

Daptomycin for methicillin-resistant Staphylococcus aureus infections of the spine

2008-12-30T07:23:00.000-08:00

Daptomycin for methicillin-resistant Staphylococcus aureus infections of the spine
Spine J. 2008 Dec 26

Burdette SD.
Department of Medicine, Wright State University Boonshoft School of Medicine, Dayton, OH 45409, USA.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infection is increasingly common. Treatment with vancomycin-based therapy is often unsuccessful. Daptomycin is a relatively new lipopeptide antibiotic with potent activity against MRSA.

PURPOSE: To describe the successful management of MRSA infection involving the spine.

STUDY DESIGN: Two case reports of MRSA infection, one involving epidural and lumbar subdural abscesses, the other with osteomyelitis and discitis.

METHODS: Two cases are described, one with lumbar epidural and subdural abscesses and the other with osteomyelitis and discitis of the spine. Switching from vancomycin to daptomycin plus rifampin-based therapy resulted in patient improvement that allowed discharge from the hospital.

RESULTS: Both patients recovered fully from their infection.

CONCLUSIONS: Daptomycin is a safe and effective option for the treatment of MRSA infection involving the spine.

PMID: 19112049 [PubMed - as supplied by publisher]

The prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in skin abscesses presenting to the pediatric emergency dep

2008-11-24T04:23:00.000-08:00

The prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in skin abscesses presenting to the pediatric emergency department.
N C Med J. 2008

Magilner D, Byerly MM, Cline DM.
Wake Forest University-School of Medicine, USA. dmagilne@wfubmc.edu

BACKGROUND: Community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) infections have been increasing. The most common of these infections present as skin abscesses. The objectives of this study were to prospectively determine the prevalence of CA-MRSA in abscesses in the population of a pediatric emergency department, to determine antibiotic sensitivity patterns of the CA-MRSA isolates, and to describe the patient population that presented with skin abscesses.

METHODS: We conducted a prospective study of children under the age of 18 years who presented to our pediatric emergency department with a skin abscess that required incision and drainage. Pus from these abscesses was sent for culture to determine the causative agent, and antibiotic sensitivities were reported. Characteristics of the patient population that presented with these abscesses were examined.

RESULTS: Sixty-eight patients were enrolled over an 18-month period. Of these, 60 (88%) had cultures positive for Staphylococcus aureus (S. Aureus). Of these 60 patients, 51 (85%) were identified as CA-MRSA by their resistance patterns. All of the CA-MRSA isolates were sensitive to trimethoprim/sulfamethoxisole; 6 (10%) were either resistant or intermittently resistant to clindamycin.

LIMITATIONS: The study was conducted on a convenience sample of patients and enrolled a relatively small number of patients.

CONCLUSIONS: CA-MRSA is responsible for the vast majority of skin abscesses presenting to the pediatric emergency department. CA-MRSA isolates are likely to be sensitive to trimethoprim/sulfamethoxisole or clindamycin, although there is some resistance to clindamycin.

PubMed

First report of methicillin-resistant Staphylococcus aureus septic arthritis complicating acupuncture

2008-11-12T06:16:00.000-08:00

First report of methicillin-resistant Staphylococcus aureus septic arthritis complicating acupuncture: simple procedure resulting in most devastating outcome.

Diagn Microbiol Infect Dis. 2008 Nov 4

Woo PC, Lau SK, Yuen KY.
State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong; Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong; Department of Microbiology, The University of Hong Kong, Hong Kong.

We report the 1st case of methicillin-resistant Staphylococcus aureus (MRSA) septic arthritis after acupuncture, with articular cartilage destruction and chronic osteomyelitis. The patient responded to arthrotomy, synovectomy, and 6 months of antibiotics. The emergence of community-associated MRSA infections would further aggravate the problem. Strict adherence to proper infection control guidelines is mandatory.

Elsevier/ScienceDirect

Methicillin-resistant Staphylococcus aureus in orthopaedic surgery.

2008-11-04T05:05:00.000-08:00

Methicillin-resistant Staphylococcus aureus in orthopaedic surgery.
J Bone Joint Surg Br. 2008 Nov

Patel A, Calfee RP, Plante M, Fischer SA, Arcand N, Born C.
Department of Orthopaedic Surgery, Brown University, Providence, Rhode Island 02903, USA. patel_amar@msn.com

Methicillin-resistant Staphylococcus aureus (MRSA) has become a ubiquitous bacterium in both the hospital and community setting. There are two major subclassifications of MRSA, community-acquired and healthcare-acquired, each with differing pathogenicity and management. MRSA is increasingly responsible for infections in otherwise healthy, active adults. Local outbreaks affect both professional and amateur athletes and there is increasing public awareness of the issue. Health-acquired MRSA has major cost and outcome implications for patients and hospitals. The increasing prevalence and severity of MRSA means that the orthopaedic community should have a basic knowledge of the bacterium, its presentation and options for treatment. This paper examines the evolution of MRSA, analyses the spectrum of diseases produced by this bacterium and presents current prevention and treatment strategies for orthopaedic infections from MRSA.

PMID: 18978255 [PubMed - in process]

Maternal-Infant Perinatal Transmission of Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus.

2008-11-04T04:52:00.000-08:00

Maternal-Infant Perinatal Transmission of Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus.
Am J Perinatol. 2008 Oct 31

Pinter DM, Mandel J, Hulten KG, Minkoff H, Tosi MF.
Department of Pediatrics, Maimonides Medical Center, Brooklyn, New York.
Because of the increasing importance of STAPHYLOCOCCUS AUREUS (SA), including methicillin-resistant SA (MRSA) in serious neonatal infections, we studied the contribution of perinatal maternal-infant transmission of SA to the colonization and infection of newborn infants. Cultures for SA, including MRSA, were obtained from nares and vagina of women in labor at term. Each mother's infant, if delivered vaginally, was cultured from nares and skin at delivery and again after 48 hours (at discharge). All MRSA and selected SA isolates were studied by pulsed field gel electrophoresis (PFGE). Infants were monitored after discharge for staphylococcal infection for 4 weeks. Of 304 women completing the study, 43 were colonized with SA, and 9/43 had MRSA. Of 252 evaluable infants, 25 were colonized with SA, and 9/25 had MRSA. Six of 252 mother-infant pairs were concordant for SA colonization, and one of these for MRSA. Isolates from five of these six infants were indistinguishable from their mother's isolates by PFGE, including the pair with MRSA. One SA-colonized infant and four noncolonized infants subsequently developed staphylococcal infections during the monitoring period. About 20% of SA isolates in this maternal population were MRSA. Perinatal maternal-infant transmission accounted for 20% of instances of perinatal colonization of infants with SA. Molecular confirmation of perinatal maternal-infant transmission of MRSA was first documented. In this population of term infants, most SA infections in the first 4 weeks of life appeared to result from colonization that occurred after discharge from the nursery.

[PubMed - as supplied by publisher]

Community acquired infections with methicillin resistant strains of Staphylococcus aureus: Report of five cases

2008-10-26T10:18:00.000-07:00

Community acquired infections with methicillin resistant strains of Staphylococcus aureus: Report of five cases
Rev Med Chil. 2008 Jul

Luis Miguel Noriega1,3, Patricia González2,3, Juan Carlos Hormazábal4, Consuelo Pinto3a, Magdalena Canals3a, José Manuel Munita1,3,5, Luis Thompson1,3, Alejandra Marcotti1,3, Jorge Pérez1,3,5, Daniel Ibáñez4, Pamela Araya4, Claudio Canals1,3, Pablo Vial1,2,3.
1Unidad de Infectología y Departamento de Medicina, Clínica Alemana, Santiago de Chile; 2Laboratorio Clínico, Clínica Alemana; 3Facultad de Medicina Clínica Alemana, Universidad del Desarrollo; 4Subdepartamento de Microbiología Clínica, Instituto de Salud Pública, Chile; 5Servicio Medicina, Hospital Padre Hurtado. Santiago de Chile. aEstudiantes de Medicina, Facultad de Medicina, Clínica Alemana, Universidad del Desarrollo

Community acquired infections with methicillin resistant strains of Staphylococcus aureus (MRSA) infections have a more aggresive clinical course and involve mostly skin and lungs. These infections appear as outbreaks among prisoners, spoñsmen, men having sex with men and military personnel. The higher aggressiveness of these strains is due to the production of several toxins, mainly Panton- Valentine leukocidine. The detection of the gene that codes for this toxin is a distinctive feature ofthese strains. We report five patients with community acquired MRSA infections. The clinicalpresentation was a skin infection in all. One patient had a pleuropneumonia in addition. Apart for resistance to beta-lactam antimicrobials, the strains were resistant to erythromycin and ciprofloxacin. Patients were treated with vancomycin, clotrimoxazole or intravenous clindamycin with a good evolution. An epidemiológical surveillance for community acquired MRSA strain infections should be started and measures to adequately treat infected patients and avoid dissemination should be implemented.

Complete Text in Spanish

SciELO

MRSA Associated with Acupuncture and Joint Injection

2008-08-12T08:04:00.000-07:00

Outbreak of Invasive Methicillin-Resistant Staphylococcus aureus Infection Associated With Acupuncture and Joint Injection.
August 2008

Murray RJ, Pearson JC, Coombs GW, Flexman JP, Golledge CL, Speers DJ, Dyer JR, McLellan DG, Reilly M, Bell JM, Bowen SF, Christiansen KJ.

From the Department of Microbiology and Infectious Diseases, PathWest Laboratory Medicine WA-Royal Perth Hospital (R.J.M., J.C.P., G.W.C, J.P.F., K.J.C.), the Division of Microbiology and Infectious Diseases, PathWest Laboratory Medicine WA-Queen Elizabeth II Medical Centre (C.L.G., D.J.S.), the Infectious Diseases Department (J.R.D., D.G.M.) and the Communicable Diseases Control Directorate, Western Australian Department of Health (S.F.B), Western Diagnostic Pathology (D.G.M), and Hands-On Infection Control (M.R.), West Perth, Perth, Western Australia , and the Department of Microbiology and Infectious Diseases, Women's and Children's Hospital, Adelaide, South Australia (J.M.B) , Australia . (Present affiliation: Clinical Services, Fremantle Hospital and Health Services, Perth, Western Australia, Australia [S.F.B.].).

Objective. To describe an outbreak of invasive methicillin-resistant Staphylococcus aureus (MRSA) infection after percutaneous needle procedures (acupuncture and joint injection) performed by a single medical practitioner.

Setting. A medical practitioner's office and 4 hospitals in Perth, Western Australia.

Patients. Eight individuals who developed invasive MRSA infection after acupuncture or joint injection performed by the medical practitioner.

Methods. We performed a prospective and retrospective outbreak investigation, including MRSA colonization surveillance, environmental sampling for MRSA, and detailed molecular typing of MRSA isolates. We performed an infection control audit of the medical practitioner's premises and practices and administered MRSA decolonization therapy to the medical practitioner.

Results. Eight cases of invasive MRSA infection were identified. Seven cases occurred as a cluster in May 2004; another case (identified retrospectively) occurred approximately 15 months earlier in February 2003. The primary sites of infection were the neck, shoulder, lower back, and hip: 5 patients had septic arthritis and bursitis, and 3 had pyomyositis; 3 patients had bacteremia, including 1 patient with possible endocarditis. The medical practitioner was found to be colonized with the same MRSA clone [ST22-MRSA-IV (EMRSA-15)] at 2 time points: shortly after the first case of infection in March 2003 and again in May 2004. After the medical practitioner's premises and practices were audited and he himself received MRSA decolonization therapy, no further cases were identified.

Conclusions. This outbreak most likely resulted from a breakdown in sterile technique during percutaneous needle procedures, resulting in the transmission of MRSA from the medical practitioner to the patients. This report demonstrates the importance of surveillance and molecular typing in the identification and control of outbreaks of MRSA infection.

Infection Control & Hospital Epidemiology

Prevention of MRSA: what hygienic measures are meaningful?]

2008-08-04T01:42:00.000-07:00

Prevention of MRSA: what hygienic measures are meaningful?
Anasthesiol Intensivmed Notfallmed Schmerzther. 2008 Jul
Kerwat K, Wulf H.
Klinik für Anästhesie und Intensivtherapie/Universitätsklinikum Giessen und Marburg.

MRSA has become a major challenge for the health system. The proportion of MRSA in the total collective of Staphylococcus aureus cases in Germany amounts to about 35 %. The further spread of MRSA must be prevented or at least slowed down. There is controversial discussion about which hygienic measures are meaningful. In Germany most people and institutions attempt to follow the recommendations of the Robert Koch Institute. These recommendations include, among others, the isolation of MRSA patients. However, this measure can only be achieved with difficulty and has limited efficacy. It may even happen that MRSA patients are treated less effectively just on account of the isolation and the other extensive measures and may more frequently experience complications. Thus it must be considered whether or not better results would be obtained without isolation when the standard hygienic protocols are strictly observed.

Thieme Connect

Methicillin-Resistant Staphylococcus aureus Infections in Collegiate Football Players.

2008-07-13T03:16:00.000-07:00

Methicillin-Resistant Staphylococcus aureus Infections in Collegiate Football Players.
Med Sci Sports Exerc. 2008 Jul 8

Bowers AL, Huffman GR, Sennett BJ.
Department of Orthopaedic Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA.

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as a serious skin infection in the athletic population. Literature in reference to football players has been sparse. We sought to better elucidate circumstances surrounding such infections in collegiate football players.

METHODS: Data from three Division-I collegiate football programs were consolidated and analyzed. Variables included presence of MRSA infection, timing of occurrence, body location involved, lesion morphology, need for surgical treatment, and antibiotic route. Data were analyzed statistically to evaluate player position, body location, and timing of occurrences.

RESULTS: Of the 491 collegiate football players, 33(6.7%) were diagnosed with MRSA infections. Cutaneous manifestations included abscess (70%), cellulitis (16%), folliculitis, impetigo, and necrotizing fasciitis. Of the infections, 90% underwent surgical drainage, whereas 27% received intravenous antibiotics. Extremity infections (n = 30) greatly exceeded truncal infections (n = 7); the most common locations were the elbow(n = 11), knee (n = 6), leg (n = 4), and forearm (n = 4). There was no difference in occurrence by player position. Infectionsoccurred predominantly in the first third of the season (P less than 0.001, chi-square test) and significantly decreased as the season progressed.

CONCLUSION: MRSA infections involving football players are becoming more common. This study documents player positions involved, timing of occurrence in the season, location and type of infections, and required treatment. Exposed extremities may predispose to infection due to risk for minor trauma and direct contact with bacteria. As infection risk seems to be independent of position, all players should observe protective measures. Although most infections occur earlier in the season, physicians should remain alert for infection occurrences throughout the season.

PubMed

Treatment of infective endocarditis caused by methicillin-resistant Staphylococcus aureus: Teicoplanin versus vancomycin in a retrospective study.

2008-06-29T05:25:00.000-07:00

Treatment of infective endocarditis caused by methicillin-resistant Staphylococcus aureus: Teicoplanin versus vancomycin in a retrospective study.

Scand J Infect Dis. 2008

Huang JH, Hsu RB.
From the Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, ROC, Taiwan.

Infective endocarditis caused by methicillin-resistant Staphylococcus aureus (MRSA) is increasing. Vancomycin and teicoplanin are 2 intravenous glycopeptides appropriate for its treatment. There is no human study comparing teicoplanin and vancomycin for the treatment of MRSA endocarditis. Between 1996 and 2006, 51 MRSA endocarditis patients were treated at the authors' hospital. There were 29 patients with nosocomial infection; 15 were treated with teicoplanin. Teicoplanin was used as the first therapeutic agent in 3 patients because of renal insufficiency. Vancomycin was used as the first therapeutic agent in 12 patients. Treatment was changed to teicoplanin because of adverse reactions in 10 and persistent bacteremia in 2 patients. Early operation was performed in 2 patients because of persistent MRSA bacteremia. Overall, 7 patients died in hospital. There was no statistically significant difference in hospital mortality rate (42% vs 47%) and bacteriologic failure rate (34% vs 40%) between 36 patients treated with vancomycin and 15 patients treated with teicoplanin. Teicoplanin can be an alternative therapy of MRSA infective endocarditis.

Informaworld

A computational model of antibiotic-resistance mechanisms in Methicillin-Resistant Staphylococcus aureus (MRSA

2008-06-27T03:09:00.000-07:00

A computational model of antibiotic-resistance mechanisms in Methicillin-Resistant Staphylococcus aureus (MRSA
J Theor Biol. 2008 Jun 4

Murphy JT, Walshe R, Devocelle M.
Modelling and Scientific Computing Group, School of Computing, Faculty of Engineering and Computing, Dublin City University, Glasnevin, Dublin 9, Ireland; Centre for Synthesis and Chemical Biology, Department of Pharmaceutical and Medicinal Chemistry, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.

An agent-based model of bacteria-antibiotic interactions has been developed that incorporates the antibiotic-resistance mechanisms of Methicillin-Resistant Staphylococcus aureus (MRSA). The model, called the Micro-Gen Bacterial Simulator, uses information about the cell biology of bacteria to produce global information about population growth in different environmental conditions. It facilitates a detailed systems-level investigation of the dynamics involved in bacteria-antibiotic interactions and a means to relate this information to traditional high-level properties such as the Minimum Inhibitory Concentration (MIC) of an antibiotic. The two main resistance strategies against beta-lactam antibiotics employed by MRSA were incorporated into the model: beta-lactamase enzymes, which hydrolytically cleave antibiotic molecules, and penicillin-binding proteins (PBP2a) with reduced binding affinities for antibiotics. Initial tests with three common antibiotics (penicillin, ampicillin and cephalothin) indicate that the model can be used to generate quantitatively accurate predictions of MICs for antibiotics against different strains of MRSA from basic cellular and biochemical information. Furthermore, by varying key parameters in the model, the relative impact of different kinetic parameters associated with the two resistance mechanisms to beta-lactam antibiotics on cell survival in the presence of antibiotics was investigated.

Elsevier Science Direct

Risk of Infection and Death due to Methicillin-Resistant Staphylococcus aureus in Long-term Carriers.

2008-06-10T07:48:00.000-07:00

Risk of Infection and Death due to Methicillin-Resistant Staphylococcus aureus in Long-term Carriers.

Clin Infect Dis. 2008 Jun

Datta R, Huang SS.
1Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, and 2Channing Laboratory, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts; 3Division of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut; and 4Division of Infectious Diseases, University of California Irvine School of Medicine, Irvine.

Background: Patients with newly acquired methicillin-resistant Staphylococcus aureus (MRSA) have significant risks of short-term morbidity and mortality due to this pathogen. We were interested in assessing whether long-term carriers have persistent risks of disease and whether all carriers, regardless of the duration of carriage, should be considered to be reasonable candidates for interventions to reduce the risk of infection. Methods. We conducted a single-center retrospective cohort study to evaluate the risk of subsequent MRSA infection and death among patients known to have harbored MRSA for at least 1 year (i.e., prevalent carriers).

Results: Among 281 prevalent carriers, 65 (23%) developed a total of 96 discrete and unrelated MRSA infections in the year after their identification as prevalent carriers. The most common infections were pneumonia (accounting for 39% of MRSA infections), soft-tissue infection (14%), and central venous catheter infection (14%). Twenty-four percent of all infections involved bacteremia. Thirty-eight MRSA infections occurred during a new hospitalization, and 32 (84%) of these infections were the reason for admission to the hospital. MRSA contributed to 14 deaths, with 6 of these deaths deemed to be attributable to MRSA. Harboring MRSA for less then 2 and MRSA colonization at the time of detection as a prevalent carrier were predictive of subsequent infection with MRSA.

Conclusions: Individuals who are known to have harbored MRSA for greater 1 year are at high risk for subsequent MRSA morbidity and mortality and should be considered to be targets for intervention, in addition to individuals who have newly acquired this pathogen.

PMID: 18532892 [PubMed - as supplied by publisher]

Health-care workers: source, vector, or victim of MRSA?

2008-05-14T05:09:00.000-07:00

Health-care workers: source, vector, or victim of MRSA?
Lancet Infect Dis. 2008 May
Albrich WC, Harbarth S.
Respiratory and Meningeal Pathogens Research Unit, Chris Hani Baragwanath Hospital, University of the Witwatersrand, Johannesburg, South Africa; Institute for Infectious Diseases, University Hospital Bern, Bern, Switzerland.

There is ongoing controversy about the role of health-care workers in transmission of meticillin-resistant Staphylococcus aureus (MRSA). We did a search of the literature from January, 1980, to March, 2006, to determine the likelihood of MRSA colonisation and infection in health-care workers and to assess their role in MRSA transmission. In 127 investigations, the average MRSA carriage rate among 33 318 screened health-care workers was 4.6%; 5.1% had clinical infections.

Risk factors included chronic skin diseases, poor hygiene practices, and having worked in countries with endemic MRSA. Both transiently and persistently colonised health-care workers were responsible for several MRSA clusters. Transmission from personnel to patients was likely in 63 (93%) of 68 studies that undertook genotyping. MRSA eradication was achieved in 449 (88%) of 510 health-care workers. Subclinical infections and colonisation of extranasal sites were associated with persistent carriage. We discuss advantages and disadvantages of screening and eradication policies for MRSA control and give recommendations for the management of colonised health-care workers in different settings.

PMID: 18471774 [PubMed - in process]

Real-time optical detection of methicillin-resistant Staphylococcus aureus using lytic phage probes.

2008-04-22T06:58:00.000-07:00

Real-time optical detection of methicillin-resistant Staphylococcus aureus using lytic phage probes.

Biosens Bioelectron. 2008 Mar 18

Guntupalli R, Sorokulova I, Krumnow A, Pustovyy O, Olsen E, Vodyanoy V.
Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, 109 Greene Hall, Auburn, AL 36849, United States.

Staphylococcus aureus (S. aureus)-specific bacteriophage was used as a probe for detection of methicillin-resistant S. aureus (MRSA) in aqueous solution using a novel optical method. Biorecognition phage monolayers transferred to glass substrates using Langmuir-Blodgett (LB) technique were exposed individually to MRSA in solution at logarithmic concentrations ranging from 10(6) to 10(9)cfu/ml, and observed for real-time binding using a CytoVivatrade mark optical light microscope system. Results indicate that LB monolayers possessed high levels of elasticity (K), measuring 22 and 29mN/m for 10(9) and 10(11)pfu/ml phage concentrations, respectively. Near-instantaneous MRSA-phage binding produced 33+/-5%, 10+/-1%, 1.1+/-0.1%, and 0.09+/-0.01% coverage of the substrate that directly correlated to a decrease in MRSA concentrations of 10(9), 10(8), 10(7), and 10(6)cfu/ml. The exclusive selectivity of phage monolayers was verified with Salmonella enterica subsp. enterica serovar typhimurium (S. typhimurium) and Bacillus subtilis.

PubMed

The Emergence of Mupirocin Resistance among Clinical Isolates of Methicillin-Resistant Staphylococcus aureus in Trinidad: a First Report.

2008-03-27T10:18:00.000-07:00

The Emergence of Mupirocin Resistance among Clinical Isolates of Methicillin-Resistant Staphylococcus aureus in Trinidad: a First Report.

Jpn J Infect Dis. 2008 Mar

Orrett FA.
Unit of Pathology and Microbiology, Faculty of Medical Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago, West Indies. drfao4301@yahoo.com.

The objective of the study was to investigate the trend of mupirocin resistance among methicillin-resistant Staphylococcus aureus (MRSA) in Trinidad. No premarketing susceptibility surveillance was ever done following the introduction of mupirocin in 1986. A total of 188 MRSA strains recovered over a 2-year period from various body sites were tested for mupirocin resistance via the disc diffusion method. The major sources of MRSA were surgical site infections (74.0%) and bloodstream infections (8.0%). High-level and low-level mupirocin resistance were detected in 26.1 and 44.1% of MRSA stains, respectively. Resistances to other non-beta-lactam antibiotics were also high. Ninety-eight percent of all MRSA were resistant to erythromycin. This was followed by resistance rates of 96.8, 95.2, 94.1, 93.6, and 93.1%, for gentamicin, ciprofloxacin, amikacin and tobramycin, co-trimoxazole, and tetracycline, respectively. No MRSA strains were found to be resistant to vancomycin, linezolid, and quinupristin-dalfopristin. The study showed that mupirocin resistance among Trinidadian MRSA strains was relatively high compared to that seen in other countries. Because of the increasing prevalence of MRSA at the San Fernando General Hospital (SFGH) and the apparently increasing resistance to mupirocin, frequent monitoring of MRSA susceptibility patterns and infection control initiatives may be helpful in reducing the incidence of MRSA with a concomitant decrease in mupirocin resistance. This report is the first after 20 years of continuous use of the drug at the SFGH.

Japanese Journal of Infectious Disease

Long-term outcomes following infection with meticillin-resistant or meticillin-susceptible Staphylococcus aureus.

2008-03-23T00:56:00.000-07:00

Long-term outcomes following infection with meticillin-resistant or meticillin-susceptible Staphylococcus aureus.
J Hosp Infect. 2008 Mar

Haessler S, Mackenzie T, Kirkland KB.
Dartmouth–Hitchcock Medical Center, Dartmouth Medical School, Lebanon, New Hampshire, USA.

Staphylococcus aureus (SA) is becoming increasingly resistant to antibiotics in hospitals and the community. Long-term outcomes following susceptible and resistant SA infection have not been studied. We performed a retrospective matched pair analysis of all patients with positive culture for meticillin-resistant SA (MRSA) or meticillin-susceptible SA (MSSA) from any site to assess the outcomes of infection. Data were collected for length of hospitalisation and in-hospital mortality, as well as longer-term outcomes including all-cause mortality, number of rehospitalisations and subsequent cultures for SA during the year following infection. Twelve months after their initial SA infection, 42% of patients were dead. There were no differences between the groups in short-term mortality, length of hospitalisation, number of subsequent hospitalisations and cultures for SA during the year following infection.

Following discharge, however, MRSA infection was associated with higher mortality than MSSA at three months (32% vs 18% P=0.02), six months (42% vs 22% P=0.002) and 12 months (51% vs 32% P=0.005). In conclusion, SA infection is associated with a high one-year all-cause mortality. Most deaths occur after discharge. The likelihood of dying during the year following infection is higher for patients with MRSA infection than for those with MSSA infection.

Elsevier

A model for surveillance of methicillin-resistant Staphylococcus aureus

2008-03-20T17:45:00.000-07:00

A model for surveillance of methicillin-resistant Staphylococcus aureus

Public Health Rep. 2008 Jan-Feb

Simons H, Alcabes P.
Hunter College, City University of New York, School of Health Sciences, New York, NY 10010, USA.

It is well recognized that methicillin-resistant Staphylococcus aureus (MRSA) has become a community pathogen. Several key differences between community-associated and hospital-associated MRSA strains exist, including distinct methicillin resistance genes and genetic backgrounds and differing susceptibility to antibiotics. Recent studies have demonstrated that typical hospital and community strains easily move between hospital and community environments. Despite evidence of MRSA's expanding reach in the community, the best methods for population-level detection and containment have not been established. In an effort to determine effective methods for monitoring the spread of MRSA, we reviewed the literature on hospital-associated and community-associated MRSA (CA-MRSA) in the community and proposed a model for enhanced surveillance. By linking epidemiologic and molecular techniques within a surveillance system that coordinates activities in the community and health-care setting, scientists and public health officials can begin to measure the true extent of CA-MRSA in communities and hospitals.

PubMed

Methicillin-Resistant Staphylococcus aureus in a Family and Its Pet Cat

2008-03-14T05:12:00.000-07:00

Methicillin-Resistant Staphylococcus aureus in a Family and Its Pet Cat

NEJM Mar 13, 2008

To the Editor: Many isolates of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) produce Panton–Valentine leukocidin (PVL), increasing the virulence of the bacteria, which can cause disseminated deep abscesses and necrotizing pneumonia.1 We report the transmission of PVL-positive MRSA between a symptomatic woman and both her asymptomatic family and their healthy pet cat.

An otherwise healthy woman presented with recurrent multiple deep abscesses. Swabs from several abscesses and nasal cultures grew MRSA that was resistant to both beta-lactam and fusidic acid antibiotics. Polymerase-chain-reaction assays for the PVL genes lukS-PV and lukF-PV were positive. The genotype of the staphylococcal chromosomal cassette was SCCmec type IV. Nasal, axillary, and inguinal cultures from her husband and their two children yielded MRSA on several occasions. Mupirocin nasal ointment and antiseptic washes were recommended for all family members. Although the patient's husband and children became MRSA-negative, the patient remained MRSA-positive. Therefore, her three apparently healthy cats were screened. Pharyngeal culture from one cat grew MRSA with the same antimicrobial resistance pattern as that of the human isolates. The clonal identity of the isolates from the family and the cats was found by typing of the spa gene repeat region and multilocus sequence typing,2,3 which showed spa-type t131 and ST80 in all isolates. This sequence combination does not correspond with that of clone USA300 (reference)

A veterinarian recommended topical decolonization of the MRSA-positive cat with ciprofloxacin and rifampin. Four weeks after the cat's treatment, screening tests of the family were negative for MRSA. Moreover, the patient's deep abscesses completely resolved. Further MRSA screening of the asymptomatic cat was declined by the family.

There is evidence that companion animals, mainly dogs, harbor MRSA,4 and interspecies MRSA transmission has been shown in the members of a family and their dog.5 This case illustrates that MRSA transmission also occurs between humans and cats. The abscesses in our patient cleared only after antibiotic treatment of the cat. It remains unclear whether the cat was the source of the patient's infection or vice versa, although spa-type t131 is extremely rare in humans.2 We conclude that pets should be considered as possible household reservoirs of MRSA that can cause infection or reinfection in humans.

Andreas Sing, M.D. Christian Tuschak, Ph.D. Stefan Hörmansdorfer, Vet.D. Bavarian Food and Health Safety Authority 85764 Oberschleißheim, Germany

New England Journal of Medicine

Woman and Cat Shared 'Super Bug'

By Serena GordonHealthDay Reporter Wed Mar 12, 11:47 PM ET
WEDNESDAY, March 12 (HealthDay News) -- People share their homes, their food and more with their pets, but one thing you probably never thought you could share with your animals is a drug-resistant staph infection.

However, according to a letter in the March 13 issue of the New England Journal of Medicine, a German family appears to have done just that. Doctors were puzzled when a woman was repeatedly treated for methicillin-resistant Staphylococcus aureus (MRSA), yet still kept coming back with the infection.

Eventually, they discovered that the family cat was harboring the dangerous bacteria, sometimes called a "super bug."

"Animals and especially pets or companion animals might serve as reservoirs for human-pathogenic bacteria," said Dr. Andreas Sing, head of the department of infectiology at the Bavarian Food and Health Safety Authority in Germany.

Before you give puss the boot, know that researchers believe it was the woman who probably initially transmitted the bacteria to the cat, not the other way around.

About 25 percent to 30 percent of Americans are colonized with staph bacteria, but only about 1 percent are colonized with MRSA, according to the U.S. Centers for Disease Control and Prevention. Most MRSA infections occur in health-care settings, such as hospitals or nursing homes, but the number of community-acquired infections is growing. According to the CDC, about 12 percent of all MRSA infections are now acquired in the community.

MRSA spreads through skin-to-skin contact with an infected person, but its transmission has also been associated with contaminated surfaces, crowded living conditions and poor hygiene, according to the CDC.

MRSA infections often look like a boil or an inflamed pimple, and may be red, swollen and draining pus, the CDC said.

The German woman was otherwise healthy, but kept getting multiple, deep abscesses. Both the abscesses and nasal swabs tested positive for MRSA. Her family members -- a husband and two children -- were also tested, and they tested positive on several occasions. Nasal ointments and antiseptic washes were prescribed for the family to "decolonize" them.

The family members then tested negative for MRSA, but the woman kept testing positive. Doctors then tested the woman's three cats, and found that one, despite having no symptoms, was carrying the same strain of MRSA. Once the cat was decolonized and both the cat and woman were retreated with antibiotics, all family members -- human and feline -- tested negative for the bacteria.

Sing and his colleagues pointed out that this is the first documented MRSA infection in a cat, although there have been reports of other animals, including dogs, harboring MRSA.

Because this infection is generally community-acquired, Sing thinks it's more likely that the woman initially transmitted the bacteria to her pet, and then the animal passed the infection back to her.

"Cats are social. They like to rub up against people and it's the skin-to-skin contact that passes MRSA," explained Dr. Matthew Sims, director of the infectious disease research program at Beaumont Hospital in Royal Oak, Mich.

But, he added, "People shouldn't start worrying about having pets. They can carry all sorts of things which we've known about forever, but you don't need to get rid of your cats or other animals."

Sims said that if you suspect you might have a MRSA infection, go to your doctor for treatment and let your doctor know if you have other people or pets in your household so your doctor can recommend appropriate treatment or prevention steps for them.

The best way to prevent these infections, Sims said, is to practice good hygiene and wash your hands frequently. If you know you have a MRSA infection, avoid direct contact with other people and animals until you've been treated.
More information

To learn more about MRSA, visit the U.S. Centers for Disease Control and Prevention.

Yahoo News

Community-associated methicillin-resistant Staphylococcus aureus skin infections: advances toward identifying the key virulence factors.

2008-03-05T21:21:00.000-08:00

Community-associated methicillin-resistant Staphylococcus aureus skin infections: advances toward identifying the key virulence factors.

Curr Opin Infect Dis. 2008 Apr

Nygaard TK, Deleo FR, Voyich JM.
aDepartment of Veterinary Molecular Biology, Montana State University, Bozeman, USA bLaboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, NIH, Hamilton, Montana, USA.

PURPOSE OF REVIEW: In recent years there has been an increase in the incidence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in healthy individuals, the cause of which is largely unknown. CA-MRSA primarily causes skin and soft-tissue infections but certain strains are also associated with unusually severe pathology. The purpose of this review is to provide a critical analysis of our current knowledge of virulence factors contributing to skin and soft-tissue infections caused by CA-MRSA.

RECENT FINDINGS: Isolates classified as pulsed-field gel electrophoresis type USA300 have emerged as the predominant CA-MRSA genotype and in most geographic areas account for 97% or more of CA-MRSA infections. Recent key studies, such as those reporting the complete genome sequence of USA300, and the discovery of cytolytic peptides that contribute significantly to CA-MRSA virulence, lead the way for future investigations.

SUMMARY: Although we have only a cursory understanding of the molecular mechanisms of CA-MRSA virulence, studies using clinically relevant CA-MRSA isolates are beginning to identify virulence determinants specific to this pathogen. Identifying CA-MRSA virulence determinants and the concerted regulation of these factors will foster development of vaccines and therapeutics designed to control CA-MRSA skin infections.

Lippincott, Williams & Wilkins

Methicillin-Resistant and -Susceptible Staphylococcus aureus Sequence Type 398 in Pigs and Humans

2008-03-02T19:01:00.000-08:00

Methicillin-Resistant and Susceptible Staphylococcus aureus Sequence Type 398 in Pigs and Humans

EID - Volume 14, Number 3–March 2008

Alex van Belkum,* Damian C. Melles,* Justine K. Peeters,* Willem B. van Leeuwen,* Engeline van Duijkeren,† Xander W. Huijsdens,‡ Emile Spalburg,‡ Albert J. de Neeling,‡ and Henri A. Verbrugh,* on behalf of the Dutch Working Party on Surveillance and Research of MRSA (SOM)1*University Medical Center Rotterdam, Rotterdam, the Netherlands; †University of Utrecht, Utrecht, the Netherlands; and ‡National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands

Nasal Staphylococcus aureus carriage has increased in pig farmers, and specific lineages of S. aureus are shared by farmers and their animals (1,2). In addition, rates of nasal carriage of methicillin-resistant S. aureus (MRSA) by veterinary personnel working with pigs is high (3–5). The pig-related MRSA appears to be clonal and was identified by multilocus sequence typing (MLST) as sequence type 398 (2,6,7). Such resistant bacterial strains can spread from animals to the environment, which may facilitate the colonization of persons who are not involved in animal husbandry (8). The porcine MRSA strain has been isolated from humans with invasive and superficial infections, and familial outbreaks of colonization and cross-colonization have been documented (2,6,7).

We sought to determine whether the clinical effect of the porcine ST398 MRSA strain can be substantiated by the existence of genetically homologous, methicillin-susceptible S. aureus (MSSA) strains among healthy or infected persons. The international MLST database (www.mlst.net) (9) listed only 1 ST398 MSSA nasal carriage isolate from a patient in Cape Verde. In addition, 1 ST398 MRSA strain was isolated from a woman living in Groningen, the Netherlands, without further clinical and epidemiologic data available. ST398 MSSA nasal carriage isolates were also identified in several pig farmers in a study by Armand-Lefevre et al. (1). We describe the population genetic analysis of Dutch community-based and nosocomial MSSA isolates in comparison with pig- and pig farmer–derived ST398 MRSA isolates, performed by spa-sequencing and amplified fragment length polymorphism (AFLP) analysis (10,11).

The Study

Most of the ST398 MRSA strains studied were collected at the Dutch Institute for Public Health and the Environment (RIVM, Bilthoven, the Netherlands). A total of 20 strains were isolated from the nares of pigs in several slaughterhouses (RIVM 21–40) (12), whereas 18 additional strains were detected during in-hospital screenings for MRSA carriage among Dutch farmers from independent farms (RIVM 1–8, 10–12 and 14–20). In addition, 8 clinical and carriage isolates were obtained from the Veterinary Medical Diagnostic Centre in Utrecht (Table).

Amplified fragment length polymorphism (AFLP) analysis was performed as described previously (10). A total of 147 marker fragments per strain were scored, and a binary table with marker absence [0] or presence [1] was constructed. A total of 30 fragments with differential occurrence, when genetically heterogeneous MSSA and ST398 MRSA fingerprints were compared, were reamplified and sequenced (Applied Biosystems, Foster City, CA, USA). Fragments were sequenced for 3 independent strains, and the consensus was analyzed by using BLAST . Typing of the staphylococcal chromosome cassette (SCCmec) and the presence of the Panton-Valentine leukocidin (PVL) genes was performed by PCR.

We embedded the genetic fingerprints of the 46 pig-related MRSA isolates in the population structure of S. aureus as obtained before (10,11). These studies include high throughput AFLP fingerprints of 829 nonclinical S. aureus human carriage isolates and 146 and 77 (including 2 MRSA isolates) clinical isolates of human and animal origin, respectively. All carriage strains were isolated from volunteers living in the Rotterdam region, where pig farms are absent.

Sequencing of the repetitive region of the protein A gene spa was performed for all ST398 MRSA isolates (13). Data were analyzed by using the Ridom Staphtype software version 1.4 .

Analysis of the AFLP data was performed as described previously (10). Both hierarchical cluster analysis and principle component analysis were performed with Spotfire Decision Site 7.2 software. We used the Fisher exact test to compare the distribution of strain categories in different phylogenetic lineages. A 2-sided p value <0.05>

The AFLP analysis of the ST398 MRSA strains derived from human and animal sources (n = 46) indicated that these strains are highly clonal. When the AFLP patterns for the ST398 strains were included in the overall population analysis for Dutch MSSA strains from carriage and infection, the distinct cluster was still observed (Figure 1). Few Dutch MSSA strains from the Rotterdam region coclustered with the ST398 pig-related MRSA isolates (Figure 1, panel B). In total, 6 (0.6%) MSSA isolates coclustered with the ST398 MRSA isolates, of which 2 were nasal carriage isolates from healthy persons (Table). Of the 6 strains, 3 were blood culture isolates taken from 3 elderly patients. All 3 patients had nosocomial bacteremia: 1 after inflammatory aneurism of the aorta, 1 during Fournier gangrene, and the last 1 after primary ventricular fibrillation. Epidemiologic data exclude a cluster of nosocomial infections; patients were not in direct contact (data not shown).

After principle component analysis , the ST398 MRSA strains still clustered as a separate group (Figure 2). The AFLP analysis did not distinguish strains from pigs or pig farmers, and only a limited number of polymorphic AFLP fragments were seen. AFLP markers that were positive for the ST398 MRSAs and absent from the other strains, or vice versa, were sequenced. Of 30 fragments analyzed, 9 were ≈100% specific for the pig-associated strains. Another 3 fragments were present in a subset of the pig-associated strains only. Of these 12 fragments, 4 were not homologous with current entries in the GenBank database, including the 10 S. aureus full-genome sequences. Of the 12 pig-specific markers, 8 were homologous with known sequences, which suggests that these markers become pig-specific by point mutations in the AFLP primer annealing site(s) rather than by genomic rearrangement. Several of the sequences encode factors were associated with membranes or transport.

The preponderance of types t011 and t108 was confirmed by spa sequencing (12). These made up >75% of all cases. However, the other types all belonged to the same family of spa types, which suggests recent drift in the sequence motifs. The t011 types are primarily associated with SCCmec IV and IVa, whereas the t108 type is nearly fully associated with SCCmec V. This finding suggests that ST398 MRSA has arisen independently on at least 2 occasions. Finally, SCCmec III is found in association with t108, t898, t567, t034, and t571. This finding suggests promiscuous dissemination of this cassette among the ST398 MRSA. Strain RIVM-17 harbored the PVL genes. Apparently, the bacteriophage carrying these genes found its way into the porcine ST398 MRSA lineage.

Conclusions

The massive colonization of Dutch pigs with a single sequence type of MRSA was unexpected (12). Molecular strain typing was initially compromised because PFGE failed (14). Spa gene sequencing (13) showed heterogeneity in the ST398 MRSA lineage with types t011 and t108, which are closely related, covering >75% of all isolates. Hence, 1 or 2 new MRSA lineages had been discovered. We found a degree of genetic association between spa types and the presence of certain SCCmec cassettes, which suggests bacterial evolution and horizontal DNA exchange in the zoonotic reservoir.

We found that ST398 is rare among Dutch MSSA strains colonizing healthy persons (2 [0.2%] of 829 strains). However, a relatively high number of MSSA isolates homologous to the ST398 MRSA were derived from bacteremic patients (3 [2.1%] of 146; p = 0.026). These 3 bacteremia isolates were not related epidemiologically; they were isolated from different patients in different medical departments over an extended period. This finding suggests that these MSSA strains are quite virulent. The strict segregation of ST398 strains (Figure 1, panel A; Figure 2) corroborates that the strains belong to a separate biotype associated with pigs (15).

Our findings pose a warning to public health surveillance: if the ST398 MSSA virulence toward humans would be maintained within the ST398 MRSA lineage from pigs, care should be taken not to introduce this strain into humans. We consider it to be likely that ST398 MRSA from pigs is capable of causing serious infection in humans even though its primary host seems to be pigs.

Dr van Belkum is with the Department of Medical Microbiology and Infectious Diseases, University Medical Center Rotterdam, Rotterdam, the Netherlands. His research interests include MRSA.

References

Armand-Lefevre L, Ruimy R, Andremont A. Clonal comparison of Staphylococcus aureus isolates from healthy pig farmers, human controls, and pigs. Emerg Infect Dis. 2005;11:711–4.
Witte W, Strommenger B, Stanek C, Cuny C. Methicillin-resistant Staphylococcus aureus ST398 in humans and animals, Central Europe. Emerg Infect Dis. 2007;13:255–8.
Hanselman BA, Kruth SA, Rousseau J, Low DE, Willey BM, McGeer A, et al. Methicillin-resistant Staphylococcus aureus colonization in veterinary personnel. Emerg Infect Dis. 2006;12:1933–8.
Voss A, Loeffen F, Bakker J, Klaassen C, Wulf M. Methicillin-resistant Staphylococcus aureus in pig farming. Emerg Infect Dis. 2005;11:1965–6.
Wulf M, van Nes A, Eikelenboom-Boskamp A, de Vries J, Melchers W, Klaassen C, et al. Methicillin-resistant Staphylococcus aureus in veterinary doctors and students, the Netherlands. Emerg Infect Dis. 2006;12:1939–41.
Ekkelenkamp MB, Sekkat M, Carpaij N, Troelstra A, Bonten MJ. Endocarditis due to meticillin-resistant Staphylococcus aureus originating from pigs [in Dutch]. Ned Tijdschr Geneeskd. 2006;150:2442–7.
Huijsdens XW, van Dijke BJ, Spalburg E, van Santen-Verheuvel MG, Heck ME, Pluister GN, et al. Community-acquired MRSA and pig-farming. Ann Clin Microbiol Antimicrob. 2006;5:26.
Gibbs SG, Green CF, Tarwater PM, Mota LC, Mena KD, Scarpino PV. Isolation of antibiotic-resistant bacteria from the air plume downwind of a swine confined or concentrated animal feeding operation. Environ Health Perspect. 2006;114:1032–7.
Feil EJ, Enright MC. Analyses of clonality and the evolution of bacterial pathogens. Curr Opin Microbiol. 2004;7:308–13.
Melles DC, Gorkink RF, Boelens HA, Snijders SV, Peeters JK, Moorhouse MJ, et al. Natural population dynamics and expansion of pathogenic clones of Staphylococcus aureus. J Clin Invest. 2004;114:1732–40.
van Leeuwen WB, Melles DC, Alaidan A, Al-Ahdal M, Boelens HA, Snijders SV, et al. Host- and tissue-specific pathogenic traits of Staphylococcus aureus. J Bacteriol. 2005;187:4584–91.
de Neeling AJ, van den Broek MJ, Spalburg EC, van Santen-Verheuvel MG, Dam-Deisz WD, Boshuizen HC, et al. High prevalence of methicillin resistant Staphylococcus aureus in pigs. Vet Microbiol. 2007;122:366–72.
Harmsen D, Claus H, Witte W, Rothganger J, Turnwald D, Vogel U. Typing of methicillin-resistant Staphylococcus aureus in a university hospital setting by using novel software for spa repeat determination and database management. J Clin Microbiol. 2003;41:5442–8.
Bens CC, Voss A, Klaassen CH. Presence of a novel DNA methylation enzyme in methicillin-resistant Staphylococcus aureus isolates associated with pig farming leads to uninterpretable results in standard pulsed-field gel electrophoresis analysis. J Clin Microbiol. 2006;44:1875–6.
Devriese LA. A simplified system for biotyping Staphylococcus aureus strains isolated from animal species. J Appl Bacteriol. 1984;56:215–20.

CDC

Prostatic Abscess Due to Community-Acquired Methicillin-Resistant Staphylococcus aureus.

2008-03-01T19:40:00.000-08:00

Prostatic Abscess Due to Community-Acquired Methicillin-Resistant Staphylococcus aureus.
Am J Med Sci. 2008 Feb

Pierce JR Jr, Saeed Q, Davis WR.
From the Department of Internal Medicine, Texas Tech University Health Sciences Center, Amarillo, Texas; and the Veterans Administration Medical Center, Amarillo, Texas.

We report what we believe to be the second case of a prostatic abscess due to community-acquired methicillin-resistant Staphylococcus aureus (MRSA). A previously healthy diabetic man presented with dysuria, fatigue, weight loss, a tender prostate, and leukocytosis. Computerized tomography of the abdomen and pelvis demonstrated a large prostatic abscess at the base of the bladder. Blood, urine, and pus obtained by percutaneous aspiration grew MRSA. Percutaneous drainage and prolonged therapy with intravenous vancomycin resulted in cure. Prostatic abscess is most often caused by Gram-negative organisms. Community-acquired MRSA, which usually causes skin and soft tissue infections, may also cause prostatic abscess. The mainstay of treatment of prostatic abscess is drainage, which can be accomplished either percutaneously or transurethrally. Gram stain and culture of the drainage will direct proper antibiotic selection.

Lippincott, Williams & Wilkins

Lemierre's Syndrome: Methicillin-Resistant Staphylococcus aureus (MRSA) Finds a New Home.

2008-03-01T19:36:00.000-08:00

Lemierre's Syndrome: Methicillin-Resistant Staphylococcus aureus (MRSA) Finds a New Home.

J Emerg Med. 2008 Feb

Bentley TP, Brennan DF.
Department of Emergency Medicine, Emergency Medicine Residency Program, Orlando Regional Medical Center, Orlando, Florida.

Lemierre's syndrome is septic thrombophlebitis of the internal jugular vein, arising as a complication of an oropharyngeal infection. This thrombophlebitis frequently results in septic emboli to organs such as the lungs. The causative agent in most previously described cases is Fusobacterium necrophorum, an anaerobic Gram-negative organism. We present the case of an 8-year-old previously healthy girl who came to the Emergency Department with a 5-day history of left-sided neck pain and was subsequently diagnosed with methicillin-resistant Staphylococcus aureus (MRSA) Lemierre's syndrome. MRSA has not previously been described in Lemierre's syndrome in the Emergency Medicine literature. The clinical presentation, findings, and management of the syndrome are discussed. Regardless of etiology, once the diagnosis of Lemierre's syndrome is made, long-term broad-spectrum intravenous therapy will be necessary.

Elsevier Science Direct

Should the Currently Recommended Twice-Daily Dosing Still be Considered the Most Appropriate Regimen for Treating MRSA Ventilator-Associated Pneumonia

2008-03-01T19:31:00.000-08:00

Should the Currently Recommended Twice-Daily Dosing Still be Considered the Most Appropriate Regimen for Treating MRSA Ventilator-Associated Pneumonia with Vancomycin?

Clin Pharmacokinet. 2008

Pea F, Viale P.
Department of Experimental and Clinical Pathology and Medicine, Institute of Clinical Pharmacology and Toxicology, Medical School, University of Udine, Udine, Italy.

Meticillin-resistant (methicillin-resistant) Staphylococcus aureus causes unacceptably high mortality from ventilator-associated pneumonia, even when appropriate early therapy with vancomycin is administered at a dosage of 15 mg/kg every 12 hours. However, because of the poor penetration of vancomycin in epithelial lining fluid, it is unlikely that this dosing schedule always achieves optimal vancomycin exposure in the lung. Conversely, there is probably enough evidence to suggest that continuous infusion enhances vancomycin efficacy with the standard 30 mg/kg daily dosage, thus avoiding the need to use higher daily dosages that could increase the risk of nephrotoxicity. It is worth noting that in the case of fully susceptible pathogens with a minimum inhibitory concentration (MIC) of /=360, so that both pharmacodynamic efficacy targets may be optimized.

PMID: 18307369 [PubMed - in process]

Prophylactic antibiotics given within 24 hours of surgery, compared with antibiotics given for 72 hours perioperatively increased rate of MRSA

2008-02-26T18:48:00.000-08:00

Prophylactic antibiotics given within 24 hours of surgery, compared with antibiotics given for 72 hours perioperatively, increased the rate of methicillin-resistant Staphylococcus aureus isolated from surgical site infections

J Infect Chemother. 2008 Feb

Kusachi S, Sumiyama Y, Nagao J, Arima Y, Yoshida Y, Tanaka H, Nakamura Y, Saida Y, Watanabe M, Watanabe R, Sato J.Third Department of Surgery, Toho University Ohashi Medical Center Hospital, 2-17-6 Ohashi, Meguro-ku, Tokyo, 153-8515, Japan, kusachi@med.toho-u.ac.jp.

The purpose of this research was to find which method better prevented MRSA isolation from postoperative infection sites: the administration of postoperative infection control agents within 72 h of surgery, including the day of surgery, or the administration of these agents within 24 h of surgery. More than 3000 patients who underwent elective surgery of the digestive system were studied. Cefazolin or cefotiam was used as the prophylactic antibiotic. The number of patients, sex, age, clinical stage, incidence of surgical site infection (SSI), isolated bacteria, distal pancreatectomy with or without gastrectomy, the rate of laparoscopic surgery, and the rate of abdominoperineal resection (APR) were examined in a prospective controlled study over three time periods. There were no significant differences in the demographics of patients in the three periods. The duration of antibiotic administration was 96.1 +/- 11.2 h in period A, 18.2 +/- 2.7 h in period B, and 66.9 +/- 11.1 hours in period C (P less then 0.05). There was no significant difference in the incidence of SSI in the three periods. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from the infectious site in 0.47% of patients in period A, and from 2.1% and 0.34% of patients in periods B and C, respectively, and the incidence of MRSA was significantly higher in period B as compared with periods A and C. The isolation rates of MRSA and methicillin-sensitive S. aureus (MSSA) were both significantly higher in period B patients. We concluded that the administration of prophylactic antibiotics within 24 h of surgery increased the rate of isolation of MRSA.

SpringerLink

Community-acquired methicillin-resistant Staphylococcus aureus: an emerging concern for physical therapists: Discussion.

2008-02-23T03:45:00.000-08:00

Community-acquired methicillin-resistant Staphylococcus aureus: an emerging concern for physical therapists: Discussion.
Physiother Res Int. 2008 Feb

Levenhagen KM.
Department of Physical Therapy, Doisy College of Health Sciences, Saint Louis University, 3437 Caroline Mall, Room 1026, St. Louis, MO 63104, USA.

The Centers for Disease Control has identified community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) as an emerging worldwide public health risk. Healthcare professionals such as physical therapists can play an important role in the early detection, prevention and management of CA-MRSA. This discussion paper is a narrative overview of CA-MRSA's prevalence in at-risk groups, the distinguishing characteristics of hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) and CA-MRSA infections, and treatments for HA-MRSA and CA-MRSA. Using the Guide to Physical Therapist Practice as a framework, this paper describes physical therapists' role in the detection, prevention and management of CA-MRSA infections and their role in community education about CA-MRSA. Copyright (c) 2008 John Wiley & Sons, Ltd.

PMID: 18288766 [PubMed - as supplied by publisher]

Daptomycin: a new treatment for insidious infections due to gram-positive pathogens (MRSA)

2008-02-23T03:42:00.000-08:00

Daptomycin: a new treatment for insidious infections due to gram-positive pathogens (MRSA)
February 2008

Cottagnoud P.
Department of Internal Medicine, Inselspital, Bern, Switzerland. Philippe.Cottagnoud@insel.ch.

Daptomycin, a new lipopeptide antibiotic, is highly bactericidal against the majority of Grampositive human pathogens, including methicillinresistant (MRSA) and vancomycin-resistant enterococci. Its mechanism of action is unique resulting in the destruction of the membrane potential without lysing the cell wall. The mechanism of action of daptomycin, its antibacterial spectrum, the development of resistance and pre- and clinical studies are discussed in this review.

PMID: 18293118 [PubMed - in process]

Rapid Diagnostics for Methicillin-Resistant Staphylococcus aureus: Current Status.

2008-02-22T15:38:00.000-08:00

Rapid Diagnostics for Methicillin-Resistant Staphylococcus aureus: Current Status.
Mol Diagn Ther. 2008

Carroll KC.
Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of healthcare- and community-associated infections, and its prevalence continues to increase. These infections are associated with morbidity and excessive mortality compared with infections caused by methicillin-susceptible S. aureus (MSSA). Numerous studies have cited the increased healthcare costs associated with MRSA infections. Infection control guidelines that combine active surveillance with aggressive patient management, such as patient isolation, decontamination, and other strategies, have been shown to reduce transmission and subsequent infections. The availability of rapid molecular diagnostics has strengthened infection control programs by providing results in hours rather than days, as the time required for culture-based methods. This review summarizes the current status of rapid diagnostic methods available for MRSA detection from nasal surveillance specimens, and assays available for rapid identification of MRSA from positive blood cultures containing Gram-positive cocci in clusters. Both amplification- and probe-based assays are highlighted and discussed in detail. Future technological advances are likely to see real-time assays that combine multiple gene targets for assessment of microbial identification, virulence detection, and mechanisms of resistance beyond mecA.

PMID: 18288879 [PubMed - in process]

USA300 MRSA may be sexually transmitted in MSM

2008-02-18T16:41:00.000-08:00

USA300 MRSA may be sexually transmitted in MSM
Male–male sex should be considered a risk factor for multidrug-resistant USA300 MRSA infection, independent of previous infection.
by Jay LewisIDN Managing Editor

February 2008

Multidrug-resistant USA300 methicillin-resistant Staphylococcus aureus may be significantly more prevalent in men who have sex with men, compared with the general population, according to the results of a recent study. The researchers hypothesized that multidrug-resistant USA300 MRSA may be sexually transmitted in this population.

The researchers conducted a population-based survey in nine hospitals in San Francisco and a cross-sectional study in two outpatient clinics in San Francisco and Boston. The researchers reviewed patients’ data to determine annual incidence, spatial clustering and risk factors for multidrug-resistant USA300 MRSA.

The results showed that the overall incidence of multidrug-resistant USA300 MRSA infection in San Francisco was 26 cases per 100,000 people. Further analysis demonstrated that incidence rates were higher in ZIP codes with a higher percentage of male same-sex couples.
The researchers determined that male–male sex should be considered a risk factor for multidrug-resistant USA300 MRSA infection, independent of previous MRSA infection. This risk also appeared to be independent of HIV status.

Study limitations

The researchers stressed that there are several limitations to the study: it only examined the multidrug-resistant USA300 strain of MRSA and did not assess patients’ sexual behavior risks.

“Our study examined the rate of infection with multidrug-resistant USA300 MRSA, which is only a subset of the usual USA300 MRSA that is susceptible to multiple antibiotics,” Christopher Graber, MD, MPH, one of the study’s researchers and member of the infectious diseases section at the VA Greater Los Angeles Healthcare System, told Infectious Disease News. “We found that this multidrug-resistant clone seemed to be concentrated in the ZIP code corresponding to the Castro district when we examined its prevalence in isolates collected from a population-based study of MRSA in San Francisco in 2004-2005. There had been results of prior studies that described a high frequency of MRSA infection in MSM, so we undertook the clinic-based studies to see if patients self-identifying as MSM were experiencing infections due to this multidrug-resistant USA300 clone more than other populations, which ended up being the case.”

Graber said more information is needed to better understand how multidrug-resistant USA300 MRSA is transmitted and why it may be infecting MSM at an increased frequency. “The retrospective nature of our study did not allow us to systematically investigate how transmission of infection exactly occurred; it only allowed us to identify the presence of multidrug-resistant USA300 MRSA in the MSM population,” Graber said. “We already know that MRSA disease can be spread by close skin-to-skin contact, and we did find that a large number of patients with infection due to multidrug-resistant USA300 MRSA had infections in the buttock/genitoperineal areas; however, we can only make an epidemiologic association and cannot definitively specify a method of transmission.”

Media attention

The study results, which are published in the Feb. 19 issue of Annals of Internal Medicine, were made available on the journal’s website in mid-January.

After its online release, the study received much attention in the mainstream media, including stories garnering headlines cautioning about a “new gay disease” and “the new HIV.” However, experts are concerned that some of this media attention may have misled the general public about the risk for multidrug-resistant USA300 MRSA.

Graber said previous reports and studies have suggested heterosexual transmission of MRSA strains. The mainstream media may be misleading the public into thinking only MSM are at risk for infection with multidrug-resistant USA300 MRSA. “USA300 MRSA is already present in the general population, and it is reasonable to expect that multidrug-resistant USA300 MRSA will spread in the general population as well,” Graber said.

According to Graber, the spread of MRSA strains can be reduced if people maintain proper personal hygiene, including regular bathing and frequent handwashing. “Routine examination of the skin is also important to identify small cuts and abrasions that could serve as points of bacterial entry,” Graber said. “Any person who has an active skin infection should keep draining wounds covered and thoroughly wash or dispose of all material that comes into contact with the wound.”

To reduce the risk for sexual transmission of MRSA strains, people are encouraged to wash with soap and water after sex, particularly if their partners show signs of active skin infection.

For more information:

Diep B, Chambers H, Graber C, et al. Emergence of multidrug-resistant, community-associated, methicillin-resistant Staphylococcus aureus clone USA300 in men who have sex with men. Ann Intern Med. http://www.annals.org/cgi/content/full/0000605-200802190-00204v1.

Infectious Disease News

Emergence of MRSA in positive blood cultures from patients with febrile neutropenia-a cause for concern.

2008-02-16T06:07:00.000-08:00

Emergence of MRSA in positive blood cultures from patients with febrile neutropenia-a cause for concern.

Support Care Cancer. 2008 Feb 15

Morris PG, Hassan T, McNamara M, Hassan A, Wiig R, Grogan L, Breathnach OS, Smyth E, Humphreys H.
Department of Oncology, Beaumont Hospital, Dublin 9, Dublin, Ireland, p_ob1_morris@yahoo.com.

GOALS OF WORK: Febrile neutropenia (FN) causes considerable morbidity in patients on cytotoxic chemotherapy. Recently, there has been a trend towards fewer Gram-negative and more Gram-positive infections with increasing antibiotic resistance. To assess these patterns, data from a supra-regional cancer centre in Ireland were reviewed.

PATIENTS AND METHODS: A 5-year review of all positive blood cultures in patients undergoing anti-cancer chemotherapy was carried out.

MAIN RESULTS: Eight hundred and ninety-four patients were reviewed. The mean incidence of FN was 64.2 cases per year. Eight hundred and forty-six blood culture specimens were taken and 173 (20.4%) were culture positive. The isolated organisms were Gram positive (71.1%), Gram negative (27.8%) and fungal (1.1%). Of the Gram-positive organisms, 75.6% were staphylococci. Of these, 67.8% were coagulase-negative staphylococci and 30.1% were Staphylococci aureus. Amongst the S. aureus, 89.3% were methicillin-resistant (MRSA). Vancomycin-resistant enterococci were not identified as a cause of positive blood cultures.

CONCLUSIONS: Amongst patients with cancer who develop FN in our hospital, Gram-positive bacteria account for the largest proportion. The high proportion of MRSA as a cause of positive blood cultures is of concern.

PMID: 18274787 [PubMed - as supplied by publisher]

MRSA and the environment: implications for comprehensive control measures

2008-02-16T06:03:00.000-08:00

MRSA and the environment: implications for comprehensive control measures

Eur J Clin Microbiol Infect Dis. 2008 Feb 14

N. Cimolai1, 2
(1)
Department of Pathology and Laboratory Medicine, Faculty of Medicine, The University of British Columbia, Vancouver, BC, V6H 3V4, Canada
(2)
Department of Pathology and Laboratory Medicine, Children’s and Women’s Centre of British Columbia, Vancouver, BC, V6H 3V4, Canada
Received: 28 September 2007 Accepted: 23 January 2008 Published online: 14 February 2008

Email: ncimolai@interchange.ubc.ca

Abstract

Environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) is established soon after colonized or infected patients become resident. There are many studies that detail the mechanisms of spread and environmental survival of methicillin-susceptible Staphylococcus aureus (MSSA); this knowledge translates directly into the same findings for MRSA. The potential ubiquity of MRSA in a health-care setting poses challenges for decontamination. Whereas patients and medical staff are important sources for MRSA spread, the environmental burden may contribute significantly in various contexts. Effective control measures must therefore include consideration for MRSA in the environment.

SpringerLink

Mortality after infection with methicillin resistant Staphylococcus aureus (MRSA) diagnosed in the community

2008-02-03T06:06:00.000-08:00

Mortality after infection with methicillin resistant Staphylococcus aureus (MRSA) diagnosed in the community
BMC Med. 2008 Jan 31

Delaney JA, Schneider-Lindner V, Brassard P, Suissa S.

Background

Outbreak reports suggest that community-acquired Methicillin-resistant Staphylococcus aureus (MRSA) infections can be life-threatening. We conducted a population based cohort study to assess the magnitude of mortality associated with MRSA infections diagnosed in the community.

Methods

We used the United Kingdomas General Practice Research Database (GPRD) to form a cohort of all patients with MRSA diagnosed in the community from 2001 through 2004 and up to ten patients without an MRSA diagnosis. The latter were frequency-matched with the MRSA patients on age, GPRD practice, and diagnosis date. All patients were older than 18 years, had no hospitalization in the 2 years prior to cohort entry, and medical history information of at least 2 years prior to cohort entry. The cohort was followed up for one year and all deaths and hospitalizations were identified. Hazard ratios of all-cause mortality were estimated using the Cox proportional hazards model adjusted for patient characteristics.

Results

The cohort included 1,439 patients diagnosed with MRSA and 14,090 patients with no MRSA diagnosis. Mean age at cohort entry was 70 years in both groups, while co-morbid conditions were more prevalent in the patients with MRSA. Within 1 year, 21.8% of MRSA patients died as compared with 5.0% of non-MRSA patients. The risk of death was increased in patients diagnosed with MRSA in the community (adjusted hazard ratio 4.1; 95% confidence interval: 3.5 to 4.7).

Conclusions

MRSA infections diagnosed in the community are associated with significant mortality in the year after diagnosis.

BMC Medicine

Reducing methicillin-resistant Staphylococcus aureus (MRSA) infections

2008-01-19T06:15:00.000-08:00

Reducing methicillin-resistant Staphylococcus aureus (MRSA) infections

Jt Comm J Qual Patient Saf. 2007 Dec
Griffin FA.
5 Million Lives Campaign, Institute for Healthcare Improvement, Cambridge, Massachusetts, USA fgriffin@ihi.org

BACKGROUND: Hospital-acquired infections from methicillin-resistant Staphylococcus aureus (MRSA) now account for more than 60% of S. aureus infections in intensive care patients reported to the Centers for Disease Control and Prevention (CDC). Media stories have raised the profile of this problem, and several states have moved toward legislative action regarding screening of hospital patients or mandatory reporting of infections. Guidelines from clinical expert organizations, including the CDC, the Association for Professionals in Infection Control and Epidemiology (APIC), and the Society for Healthcare Epidemiology of America (SHEA), recommend the use of basic prevention practices to avoid transmission in the hospital setting, yet concerns persist that compliance with these practices is neither consistent nor reliable.

INTERVENTION: The campaign's MRSA intervention recommends five key components of care. These are not intended to be an all-inclusive list but rather have been recommended by experts as the minimum necessary components:

(1) hand hygiene
(2) decontamination of the environment and equipment
(3) active surveillance
(4) contact precautions for infected and colonized patients, and
(5) device bundles (central line bundle and ventilator bundle).

CONCLUSION: The IHI's 5 Million Lives Campaign considers all hospital-acquired infections as harm to patients, and reduction of MRSA is one of the areas of focus.

PMID: 18200897 [PubMed - in process]

Optimizing therapy for MRSA pneumonia

2007-12-24T04:35:00.000-08:00

Optimizing therapy for MRSA pneumonia

Semin Respir Crit Care Med. 2007 Dec

Skrupky LP, Micek ST, Kollef MH.
Department of Pharmacy, Barnes-Jewish Hospital. St. Louis, Missouri.

With its remarkable armamentarium of resistance and virulence factors, STAPHYLOCOCCUS AUREUS has emerged as a dominant pathogen causing pneumonia of all classifications. Rates of methicillin resistance are increasing as clinicians struggle to find ways to prevent the acquisition of methicillin-resistant STAPHYLOCOCCUS AUREUS (MRSA) and to effectively treat MRSA pneumonia. Community-associated MRSA has been identified as an important subset of MRSA with unique characteristics. Vancomycin remains a recommended first-line therapy for MRSA pneumonia, but resistance and therapeutic failures with vancomycin are being increasingly reported. Factors associated with vancomycin success or failure have been identified, including the genetics of the MRSA isolate, vancomycin lung penetration, minimum inhibitory concentration, and pharmacokinetic and pharmacodynamic variables. Retrospective analyses suggest that linezolid may provide improved outcomes compared with vancomycin for MRSA pneumonia, but validation in a prospective trial is currently lacking. Other treatment options are limited, but new prospects are being investigated. This paper reviews the epidemiology and pharmacotherapy of MRSA pneumonia.

Thieme Connect

The Increasing Problem of Wound Bacterial Burden and Infection in Acute and Chronic Soft-Tissue Wounds Caused by Methicillin-Resistant Staphylococcus

2007-12-21T01:43:00.000-08:00

The Increasing Problem of Wound Bacterial Burden and Infection in Acute and Chronic Soft-Tissue Wounds Caused by Methicillin-Resistant Staphylococcus aureus.

J Burns Wounds. 2007

Demling RH, Waterhouse B.
Brigham and Women's Hospital, Burn and Trauma Center, Boston, MA.

Methicillin-resistant Staphylococcus aureus (MRSA) has become a leading cause of colonization and infection in both acute and chronic soft-tissue wounds. Objective: Our objective is to define this current epidemic problem caused by both community-acquired MRSA (CA-MRSA) and hospital-acquired MRSA (HA-MRSA), focusing on the similarities and differences between these 2 isolates as well as the impact on wound management decisions. Methods: Methods used include a literature review on the growth of the current MRSA problem and its International scope. In addition, a current up-to-date assessment had been made of the problem and the current approach to management of MRSA in acute soft-tissue and chronic wounds. Burns are not discussed because this injury usually does not fit either categories and is managed quite uniquely. Results: Results included the following: (1) There are very distinct properties of CA-MRSA and HA-MRSA, which must be considered for acute and chronic wound care. Management of both requires rigorous barrier precaution techniques to avoid cross-contamination. The presence of MRSA as a carrier state increases the risk of both a systemic and local wound infection in the carrier. There are large and increasing reservoirs of CA-MRSA and HA-MRSA worldwide leading to more bacteremias and wound problems. Topical antimicrobial therapy has not been addressed in managing MRSA in acute and chronic wounds. Conclusion: Conclusions include the fact that both HA-MRSA and CA-MRSA wound infections are rapidly increasing, especially with CA-MRSA. This high incidence requires appropriate wound prediction and management decisions as well as attempts to avoid further cross-contamination and reservoir growth. Topical antimicrobial therapy would seem to be an important component in controlling this tremendous problem. Yet this topic has yet to be adequately addressed.

PMID: 18091985 [PubMed - in process]

Pharmacokinetics and Pharmacodynamics of Ceftobiprole, an Anti-MRSA Cephalosporin with Broad-Spectrum Activity

2007-12-15T03:54:00.000-08:00

Pharmacokinetics and Pharmacodynamics of Ceftobiprole, an Anti-MRSA Cephalosporin with Broad-Spectrum Activity
Clin Pharmacokinet. 2008

Murthy B, Schmitt-Hoffmann A.
Clinical Pharmacology and Experimental Medicine, Johnson & Johnson Pharmaceutical Research & Development, LLC, Raritan, New Jersey, USA.

Ceftobiprole, a beta-lactam, is the first of a new generation of broad-spectrum cephalosporins in late-stage development with activity against methicillin-resistant Staphylococcus aureus (MRSA) in addition to broad-spectrum bactericidal activity against other Gram-positive and Gram-negative pathogens. The prodrug, ceftobiprole medocaril, is converted rapidly and almost completely to the active drug, ceftobiprole, upon infusion by type A esterases. In humans, ceftobiprole binds minimally (16%) to plasma proteins, and binding is independent of the drug and protein concentrations. Its steady-state volume of distribution (18.4 L) approximates the extracellular fluid volume in humans. Ceftobiprole undergoes minimal hepatic metabolism, and the primary metabolite is the beta-lactam ring-opened hydrolysis product (open-ring metabolite). Systemic exposure of the open-ring metabolite accounts for 4% of ceftobiprole exposure following single-dose administration; approximately 5% of the dose is excreted in the urine as the metabolite. Ceftobiprole does not significantly induce or inhibit relevant cytochrome P450 enzymes and is neither a substrate nor an inhibitor of P-glycoprotein. Ceftobiprole is rapidly eliminated, primarily unchanged, by renal excretion, with a terminal elimination half-life of 3 hours; the predominant mechanism responsible for elimination is glomerular filtration, with approximately 89% of the dose being excreted as the prodrug, active drug (ceftobiprole) and open-ring metabolite. The pharmacokinetics of ceftobiprole are linear following single and multiple infusions of 125-1000 mg. Steady-state drug concentrations are attained on the first day of dosing, with no appreciable accumulation when administered three times daily (every 8 hours) and twice daily (every 12 hours) in subjects with normal renal function. Low intersubject variability has been seen across studies. Ceftobiprole exposure is slightly higher (~15%) in females than in males; this difference has been attributed to bodyweight. However, the pharmacodynamics of ceftobiprole are similar in males and females, and dosing adjustments are not required based on gender. In patients with moderate to severe renal impairment, systemic clearance of ceftobiprole correlated well with creatinine clearance. For these patients, dose adjustments for the treatment of infections caused by target pathogens, including MRSA, should be based on creatinine clearance. Ceftobiprole is undergoing clinical evaluation in phase III trials in patients with complicated skin and skin structure infections, patients with nosocomial pneumonia, and community-acquired pneumonia in hospitalized patients.

PMID: 18076216 [PubMed - in process]

Public computer surfaces are reservoirs for methicillin-resistant staphylococci.

2007-11-30T03:11:00.000-08:00

Public computer surfaces are reservoirs for methicillin-resistant staphylococci.

ISME J. 2007 Jul

Kassem II, Sigler V, Esseili MA.
1Laboratory for Microbial Ecology, Department of Environmental Sciences, University of Toledo, Toledo, OH, USA.

The role of computer keyboards used by students of a metropolitan university as reservoirs of antibiotic-resistant staphylococci was determined. Putative methicillin (oxacillin)-resistant staphylococci isolates were identified from keyboard swabs following a combination of biochemical and genetic analyses. Of 24 keyboards surveyed, 17 were contaminated with staphylococci that grew in the presence of oxacillin (2 mg l(-1)). Methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA), -S. epidermidis (MRSE) and -S. hominis (MRSH) were present on two, five and two keyboards, respectively, while all three staphylococci co-contaminated one keyboard. Furthermore, these were found to be part of a greater community of oxacillin-resistant bacteria. Combined with the broad user base common to public computers, the presence of antibiotic-resistant staphylococci on keyboard surfaces might impact the transmission and prevalence of pathogens throughout the community.The ISME Journal (2007) 1, 265-268; doi:10.1038/ismej.2007.36; published online 31 May 2007.

PMID: 18043636 [PubMed - in process]

Methicillin-Resistant Staphylococcus Aureus Carriage, Infection and Transmission in Dialysis Patients, Healthcare Workers and their Family Members.

2007-11-22T04:48:00.001-08:00

Methicillin-Resistant Staphylococcus Aureus Carriage, Infection and Transmission in Dialysis Patients, Healthcare Workers and their Family Members.

Nephrol Dial Transplant. 2007

Lu PL, Tsai JC, Chiu YW, Chang FY, Chen YW, Hsiao CF, Siu LK.
1Department of Internal Medicine, Kaohsiung Medical University Hospital.

BACKGROUND: Carriage and subsequent infection with methicillin resistant S. aureus (MRSA) and its transmission between hospital and community settings have not been studied in dialysis patients and their contacts.

METHODS: Surveillance for nasal MRSA carriage and infection among dialysis patients, healthcare workers (HCWs) and their family members in a dialysis centre was prospectively undertaken during three time periods within 1 year. Molecular typing was used to determine epidemiological relationship.

RESULTS: Among 1687 samples collected, MRSA colonization rates were 2.41% (2/83) for peritoneal dialysis patients and 2.36% (12/509) for haemodialysis patients. Five (5/14) subjects subsequently had MRSA infection. The clinical MRSA isolates had the same molecular type as the colonized strains of the same person, indicating MRSA colonization preceded clinical infection. Significantly higher MRSA nasal carriage rates were observed among family members of HCWs than family members of dialysis patients (P = 0.0024). Only three major clones were observed. Pulmonary diseases (OR: 4.873, 95% CI: 1.668-14.235), recent admission to a hospital (OR: 2.797, 95% CI: 1.291-6.059) and recent antibiotics usage (OR: 2.319, 95% CI: 1.053-5.104) were also significantly associated with MRSA carriage.

CONCLUSION: Transmission of MRSA among dialysis patients, HCWs and their family members in a dialysis unit could be inferred. Monitoring and eradication of MRSA from patients, HCWs and their family members should be considered to prevent continuous spread between healthcare facilities and the community.

PMID: 18029375 [PubMed - as supplied by publisher]

Most MRSA infections in the United States are health care-associated

2007-11-20T14:12:00.000-08:00

Most MRSA infections in the United States are health care-associated
Nov 20, 2007

Community-associated cases not the majority but are still responsible for invasive infections and, rarely, death.
by Michelle StephensonIDN Correspondent

November 2007

Invasive methicillin-resistant Staphylococcus aureus infections are a major public health problem. Recent study results found that although they are primarily health care-associated, they are no longer confined to a particular type of institution.

Researchers from across the country recently participated in a study to describe the incidence and distribution of invasive MRSA. The Active Bacterial Core surveillance system is an ongoing, population-based, active laboratory surveillance system, and it is a part of the Emerging Infections Program of the CDC. For this study, researchers from several Emerging Infections Program sites conducted surveillance for invasive MRSA infections from July 2004 through December 2005.

The sites included the Atlanta metropolitan area; Baltimore City; the state of Connecticut; Davidson County, Tennessee; the Denver metropolitan area; Monroe County, New York; the Portland, Oregon metropolitan area; Ramsey County (the St. Paul area), Minnesota and the San Francisco Bay Area. In 2005, the total population under surveillance was approximately 16.5 million people, or approximately 5.6% of the U.S. population.

Incidence rates

Between July 2004 and December 2005, there were 8,987 reported cases of invasive MRSA. Most were health care-associated, with 5,250 (58.4%) community-onset, health care-associated infections; 2,389 (26.6%) hospital-onset, health care-associated infections; 1,234 (13.7%) community-associated infections and 114 (1.3%) that could not be classified.

In 2005, the standardized incidence rate of invasive MRSA was 31.8 per 100,000, and the standardized mortality rate was 6.3 per 100,000. People who were aged 65 years or older had the highest incidence rates (127.7 per 100,000), followed by blacks (66.5 per 100,000) and men (37.5 per 100,000). Children aged 5 to 17 years had the lowest incidence rates (1.4 per 100,000).

Of the total number of patients with MRSA infection, 1,598 died while they were inpatients.

The unadjusted incidence rates of all types of invasive MRSA infections ranged from approximately 20 to 50 per 100,000; however, rates were remarkably higher in Baltimore City (116.7 per 100,000).

The incidence rate of invasive CA-MRSA was five per 100,000 or fewer in all of the sites, and incidence rates were consistently higher among blacks compared with whites in all age groups.

The rate of health care-associated, community-onset MRSA infections was 17.6 per 100,000, which was greater than either health care-associated, hospital-onset infections (8.9 per 100,000) or community-associated infections (4.6 per 100,000). Among patients with MRSA, the mortality rate for health care-associated, community-onset infections was higher (3.2 per 100,000) than for health care-associated, hospital-onset infections (2.5 per 100,000) or for community-associated infections (0.5 per 100,000).

“For the first time, we have a measurement of the burden and distribution of invasive MRSA infections. Given that the majority [of cases] were health care-associated, we need to step up our prevention efforts in health care facilities. The findings also suggest that, in 2005, community-associated cases had invasive infections at a rate of five per 100,000 and death at a rate of 0.5 per 100,000: not the majority but not trivial,” said Monina Klevens, DDS, from the CDC, who was a researcher of the study. The study results were recently published in the Journal of the American Medical Association.

During 2005, 5,287 MRSA infections were reported in the surveillance areas, and after adjusting for age, race, and sex and applying these numbers to the total U.S. population, the researchers estimated that 94,360 patients had an invasive MRSA infection. During 2005, 988 patients died of invasive MRSA infections. After adjusting these numbers to the total U.S. population, the researchers estimated that there were 18,650 in-hospital deaths due to invasive MRSA infections.

Risk factors for MRSA

During the study period, 4,105 (78.2%) of the 5,250 patients with health care-associated, community-onset infections and 1,993 (83.4%) of the 2,389 patients with health care-associated, hospital-onset infections had more than one health care risk factor for MRSA documented in their medical records. The most common health care risk factors among patients with community-onset infections were a history of hospitalization (76.6%), long-term care residence (38.5%), history of surgery (37.0%) and MRSA infection or colonization (30.3%). The most common health care risk factors among patients with hospital-onset infections were a history of hospitalization (57.7%), history of surgery (37.6%), long-term care residence (21.9%) and MRSA infection or colonization (17.4%).

Of the 8,987 observed cases of invasive MRSA, 8,792 cases had complete information in their charts, and of these, the clinical syndrome associated with invasive MRSA disease included bacteremia (75.2%), pneumonia (13.3%), cellulitis (9.7%), osteomyelitis (7.5%), endocarditis (6.3%) and septic shock (4.3%). Of the patients, 8,304 (92.4%) were hospitalized. Additionally, 1,598 (17.8%) of the patients died during hospitalization, and 1,162 (12.9%) of the patients developed recurrent invasive infections.

Ninety-eight percent of patients had a recorded clinical outcome. Interestingly, mortality rates varied according to MRSA-related diagnosis. Patients with septic shock had a high mortality rate of 55.6%; for patients with pneumonia, 32.4%. Patients with endocarditis had a moderate mortality rate of 19.3%; for patients with bacteremia, 10.2%. Patients with cellulitis had a low mortality rate (6.1%).

Pulsed-field typing

The results of pulsed-field gel electrophoresis were available for 864 (71.9%) of the 1,201 isolates received from eight of the nine study sites. Most (81.6%) of the results were from blood cultures, 4.8% from synovial fluid, 4.7% from bone, 1.9% from pleural fluid, 1.5% from peritoneal fluid and 5.5% from other normally sterile sites. Isolates tested were associated with uncomplicated bacteremia (69.8%), pneumonia (19.3%), cellulitis (11.3%), osteomyelitis (10.4%), endocarditis (8.5%) and septic shock (5.0%).

For two-thirds (66.6%) of the isolates from community-associated cases, USA300 was the strain type identified. It was also identified among 22.2% of the isolates from health care-associated, community-onset cases and among 15.7% of health care-associated, hospital-onset cases. USA100 was the strain type found in 35 (23.0%) of the 150 isolates from community-associated cases.

“One of the interesting findings from this study was the report that the USA300 clone, the most common community-associated MRSA strain, caused not only community-associated infection but also health care-associated infection. The epidemiology of MRSA continues to evolve and becomes more and more complex. The frequency of MRSA in the community and hospital and its effect on poor clinical outcomes will hopefully lead to improved hand and personal hygiene,” said Keith S. Kaye, MD, medical director of the hospital infection control committee, Duke University Medical Center, Durham, N.C., and member of the Infectious Disease News editorial advisory board.

Denise M. Cardo, MD, director of the division of health care quality promotion at the CDC’s National Center for Preparedness, Detection and Control of Infectious Diseases, and member of the Infectious Disease News editorial advisory board, also stressed the importance of infection prevention measures. “MRSA is an important problem in health care settings and is a threat to your patients. Most MRSA invasive infections are health care-associated, and these infections can be prevented with adherence to infection prevention recommendations during all patient encounters,” said Cardo.

Because the main mode of transmission of MRSA is the hands, standard precautions such as hand hygiene and gloving are imperative.

For more information:

Klevens RM, Morrison MA, Nadle J, et al. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA. 2007;298:1763-1771.

Infectious Disease News

Key to MRSA Virulence in Community Discovered

2007-11-16T05:02:00.000-08:00

Key to MRSA Virulence in Community Discovered

Bacteria target immune system cells sent to kill them, study finds

Monday, November 12, 2007

MONDAY, Nov. 12 (HealthDay News) -- Researchers have uncovered a cache of molecular weapons that helps make community-associated methicillin-resistant Staphylococcus aureus (MRSA) so virulent.

Though more work must be done, the study "provides a partial explanation of why these strains are so successful in causing infection and gives a starting point in the development of new drug treatments," said Dr. Gregory Moran, a professor of medicine in the departments of emergency medicine and infectious disease at the Olive View-UCLA Medical Center.

Michael Otto, a senior investigator at the National Institute of Allergy and Infectious Disease, Rocky Mountain Laboratories, and his colleagues searched for and found a battery of short, novel peptides that are expressed by community-associated MRSA strains at higher levels than their hospital-associated MRSA cousins.

Deleting the genes encoding these peptides in mouse models of bacterial infection reduced the microbes' ability to kill or induce skin lesions in infected animals, while purified peptides paralyzed -- and paradoxically, activated -- neutrophils, which are the white blood cells whose job it is to prevent bacterial infections and the principal component of pus.

The study was published in the Nov. 11 online issue of Nature Medicine.

According to the U.S. Centers for Disease Control and Prevention, S. aureus, commonly found on the skin and in the nose of healthy individuals, is associated with bacterial skin infections. MRSA, as its name implies, is a particularly nasty strain of S. aureus that is resistant to the class of antibiotics that includes penicillin, amoxicillin and methicillin.

Traditionally, MRSA, which can cause boils, skin necrosis and even death, has been limited to hospital settings and crowded environments such as prisons. Yet, beginning in 1999, community-associated cases of the disease have been on the rise. Last month, a study in the Journal of the American Medical Association found that more people died of MRSA than of AIDS in 2005.

"That [sudden increase] was alarming, and nobody knew why it was happening," said Moran, who co-authored a 2006 study showing that community-associated MRSA accounts for almost 60 percent of skin infections that require a visit to the emergency room. "Something about these strains made them very well-suited to spread throughout the population."

These peptides could explain that virulence, at least in part, said Philip Tierno, director of clinical microbiology & immunology at New York University Medical Center and author of The Secret Life of Germs: Observations and Lessons From a Microbe Hunter."

"Virulence, it seems, is caused by these peptides, which can kill phagocytic cells [neutrophils], which come to your defense when staph is invading your body," he explained.

Staphylococci, Tierno noted, induce pus formation by recruiting and activating white blood cells. "That very induction of phagocytes [neutrophils] is key to your successful eradication of the organisms in the body," he said. However, "Staph has a defense. These peptides that can kill these phagocytic cells, thereby rendering you defenseless."

The genes encoding these toxins are found in the genomes of all sequenced MRSA strains, but community-associated MRSA strains produced the toxins at higher levels than the hospital strains, which typically cannot infect healthy individuals. Thus, they may explain the enhanced virulence of the community-associated strains.

The bacteria would fly under the immune system's radar, so to speak, by not expressing the peptides until the bacteria were either present in very large numbers, or perhaps after being engulfed by neutrophils and enclosed in a small space.

In either case, the mechanism would detect that situation and begin production of the peptides in earnest to fight back against the immune system.

"From the bacterial point of view, the most important thing is to get rid of the neutrophil," Otto said.

According to Moran, these findings suggest new drug possibilities -- antibodies that can remove the peptides from circulation, for instance.

"Any time we can better understand the basic physiology of how infections get around the immune system, it gives a potential target for treatment," he said.

However, Tierno emphasized that focusing exclusively on these peptides would be a mistake, as they represent just one of many mechanisms by which virulent MRSA can harm their hosts; these strains also express toxins that can overwhelm the body in other ways.

"All of these work together to make the organism so deadly," Tierno said. "There is a synergy without question that accounts for a big problem with these organisms."

HealthDay

Subtle genetic changes enhance virulence of methicillin resistant and sensitive Staphylococcus aureus MRSA

2007-11-15T15:42:00.000-08:00

Subtle genetic changes enhance virulence of methicillin resistant and sensitive Staphylococcus aureus.

BMC Microbiol. 2007 Nov 6;
ABSTRACT:

BACKGROUND: Community acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) increasingly causes disease worldwide. USA300 has emerged as the predominant clone causing superficial and invasive infections in children and adults in the USA. Epidemiological studies suggest that USA300 is more virulent than other CA-MRSA. The genetic determinants that render virulence and dominance to USA300 remain unclear.

RESULTS: We sequenced the genomes of two pediatric USA300 isolates: one CA-MRSA and one CA-methicillin susceptible (MSSA), isolated at Texas Children's Hospital in Houston. DNA sequencing was performed by Sanger dideoxy whole genome shotgun (WGS) and 454 Life Sciences pyrosequencing strategies. The sequence of the USA300 MRSA strain was rigorously annotated. In USA300, MRSA 2685 chromosomal open reading frames were predicted and 3.1 and 27 kilobase (kb) plasmids were identified. USA300 MSSA contained a 20 kb plasmid with some homology to the 27 kb plasmid. Two regions found in US300 MRSA were absent in USA300 MSSA. The USA300 sequence was aligned with other sequenced S. aureus genomes and regions unique to USA300 MRSA were identified.

CONCLUSIONS: USA300-MRSA is highly similar to other MRSA strains based on whole genome alignments and gene content, indicating that the differences in pathogenesis are due to subtle changes rather than to large-scale acquisition of virulence factor genes. The USA300 Houston isolate differs from another sequenced USA300 strain isolate, derived from a patient in San Francisco, in plasmid content and a number of sequence polymorphisms. Such differences will provide new insights into the evolution of pathogens.

BioMed Microbiology

Environmental contamination makes an important contribution to hospital infection.

2007-11-07T03:00:00.000-08:00

Environmental contamination makes an important contribution to hospital infection.
J Hosp Infect. 2007 Jun;65

Boyce JM.
Infectious Diseases Section, Hospital of Saint Raphael, New Haven, USA.

KEYWORDS: Environmental contamination; MRSA; VRE; Hydrogen peroxide vapour

Meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are capable of surviving for days to weeks on environmental surfaces in healthcare facilities. Environmental surfaces frequently touched by healthcare workers are commonly contaminated in the rooms of patients colonized or infected with MRSA or VRE. A number of studies have documented that healthcare workers may contaminate their hands or gloves by touching contaminated environmental surfaces, and that hands or gloves become contaminated with numbers of organisms that are likely to result in transmission to patients. Pathogens may also be transferred directly from contaminated surfaces to susceptible patients. There is an increasing body of evidence that cleaning or disinfection of the environment can reduce transmission of healthcare-associated pathogens. Because routine cleaning of equipment items and other high-touch surfaces does not always remove pathogens from contaminated surfaces, improved methods of disinfecting the hospital environment are needed. Preliminary studies suggest that hydrogen peroxide vapour technology deserves further evaluation as a method for decontamination of the environment in healthcare settings.

Elsevier

Importance of the environment in meticillin-resistant Staphylococcus aureus acquisition: the case for hospital cleaning

2007-11-07T02:56:00.000-08:00

Importance of the environment in meticillin-resistant Staphylococcus aureus acquisition: the case for hospital cleaning
Review

Dr Stephanie J Dancer MDa, , aDepartment of Microbiology, Southern General Hospital, Glasgow, UK Available online 31 October 2007.

Summary

In the UK, we continue to debate the importance of hospital cleaning in relation to increasing numbers of patients acquiring meticillin-resistant Staphylococcus aureus (MRSA). However, there is little direct evidence for the effectiveness of cleaning because it has never been afforded scientific status. Hospital hygiene is usually assessed visually, but this does not necessarily correlate with microbiological risk. A more robust case for hospital cleaning can be presented by considering the evidence for all the stages of the staphylococcal transmission cycle between human beings and their environment. Cleaning has already been accepted as an important factor in the control of other hardy environmental pathogens, such as Clostridium difficile, vancomycin-resistant enterococci, norovirus, and Acinetobacter spp. This Review will show why the removal of dirt might have more impact on the control of MRSA than previously thought. Introduction of additional cleaning services is easier than improvements in hand-hygiene compliance.

The Lancet Infectious Diseases

Invasive methicillin-resistant Staphylococcus aureus infections in the United States.

2007-11-05T12:24:00.000-08:00

Invasive methicillin-resistant Staphylococcus aureus infections in the United States.

JAMA. 2007 Oct 17

Klevens RM, Morrison MA, Nadle J, Petit S, Gershman K, Ray S, Harrison LH, Lynfield R, Dumyati G, Townes JM, Craig AS, Zell ER, Fosheim GE, McDougal LK, Carey RB, Fridkin SK; Active Bacterial Core surveillance (ABCs) MRSA Investigators.

Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. rmk2@cdc.gov

CONTEXT: As the epidemiology of infections with methicillin-resistant Staphylococcus aureus (MRSA) changes, accurate information on the scope and magnitude of MRSA infections in the US population is needed.

OBJECTIVES: To describe the incidence and distribution of invasive MRSA disease in 9 US communities and to estimate the burden of invasive MRSA infections in the United States in 2005.

DESIGN AND SETTING: Active, population-based surveillance for invasive MRSA in 9 sites participating in the Active Bacterial Core surveillance (ABCs)/Emerging Infections Program Network from July 2004 through December 2005. Reports of MRSA were investigated and classified as either health care-associated (either hospital-onset or community-onset) or community-associated (patients without established health care risk factors for MRSA).

MAIN OUTCOME MEASURES: Incidence rates and estimated number of invasive MRSA infections and in-hospital deaths among patients with MRSA in the United States in 2005; interval estimates of incidence excluding 1 site that appeared to be an outlier with the highest incidence; molecular characterization of infecting strains.

RESULTS: There were 8987 observed cases of invasive MRSA reported during the surveillance period. Most MRSA infections were health care-associated: 5250 (58.4%) were community-onset infections, 2389 (26.6%) were hospital-onset infections; 1234 (13.7%) were community-associated infections, and 114 (1.3%) could not be classified. In 2005, the standardized incidence rate of invasive MRSA was 31.8 per 100,000 (interval estimate, 24.4-35.2). Incidence rates were highest among persons 65 years and older (127.7 per 100,000; interval estimate, 92.6-156.9), blacks (66.5 per 100,000; interval estimate, 43.5-63.1), and males (37.5 per 100,000; interval estimate, 26.8-39.5). There were 1598 in-hospital deaths among patients with MRSA infection during the surveillance period. In 2005, the standardized mortality rate was 6.3 per 100,000 (interval estimate, 3.3-7.5). Molecular testing identified strains historically associated with community-associated disease outbreaks recovered from cultures in both hospital-onset and community-onset health care-associated infections in all surveillance areas.

CONCLUSIONS: Invasive MRSA infection affects certain populations disproportionately. It is a major public health problem primarily related to health care but no longer confined to intensive care units, acute care hospitals, or any health care institution.

PMID: 17940231 [JAMA]

How staph became drug-resistant threat

2007-11-04T07:14:00.000-08:00

How staph became drug-resistant threat

Sunday November 4, 2007

94,000 infections a year, many occurring outside of hospitals

By Jeremy Manier Tribune staff reporter

The evolutionary path of the bacterium called MRSA wound around the globe for decades before a pair of Chicago doctors in 1996 noticed the bug had taken an ominous turn.

Before then, the germ's resistance to antibiotics was of concern mainly in hospitals, where steadily growing numbers of patients were contending with the stubborn staph infection. Reports of healthy people who contracted MRSA outside of a hospital were rare and isolated, the stuff of obscure medical journal articles.

But the bacterium, formally known as methicillin-resistant Staphylococcus aureus, was beginning to depart from the habits it had settled into during years of adaptation to human hosts.

At the University of Chicago Medical Center, pediatric specialists Dr. Robert Daum and Dr. Betsy Herold held an impromptu meeting to discuss a dramatic increase in young patients showing up at the hospital with MRSA infections they'd gotten in the community. Dozens of children were sickened by the resistant bacteria without having contact with hospitals -- an unprecedented outbreak.

"We just looked at each other and said, 'What's going on here?'" said Daum, chief of pediatric infectious diseases at the U. of C.

They were witnessing a pivotal episode in the biography of a bacterial family that is now found widely in hospitals and among the public at large, causing 94,000 severe infections each year with 19,000 deaths, according to a recent federal estimate. From its humble birth at hospitals in Britain, MRSA has transformed itself into a menacing microbe with fewer weaknesses and perhaps more lethal power than its ancestors had.

The germ's years of adaptation did not make it an invulnerable superbug. Some antibiotics still work reliably against MRSA and even severe cases of illness can be treated. But many doctors still do not know how to recognize and properly treat the infection, and experts are concerned potent strains will continue spreading in the community.

The bug's erratic evolutionary story became clear only in the last few years as scientists decoded the full genomes of at least 12 separate staph varieties, making the bacteria among the most intensely studied pathogens in recent memory. Genetic sleuthing has revealed MRSA's family ties and some potential gaps in its armor, as well as the darker corridors of its private life.

Like most successful germs, MRSA has triumphed by constantly changing and adapting to new environments. MRSA does this mostly through an uncanny talent for weird bacterial sex.

It's not sex as humans understand the term, but the effect is the same: a blending of genes from unrelated individuals. MRSA does it with the aid of viruses that siphon DNA from an individual germ and inject it into the next, like microscopic mosquitoes. The bacterium also has the ghoulish ability to suck up genetic material from germs that have died and dissolved.

"This isn't like human biology at all -- after we're born we're stuck with the genes we've got," said MRSA researcher Dr. Henry Chambers, chief of infectious diseases at San Francisco General Hospital. "Staph can take on new genes and share them with friends."

The bacterial ancestors of MRSA have probably stalked humans throughout history. Staph is an ancient, ball-shaped germ that caused skin inflammation and battlefield wound infections long before it encountered the antibiotics that helped spawn MRSA. Scientists identified Staphylococcus aureus as a species in the late 19th Century.

Staph felt the sting of antibiotics before any other bacteria, when British researcher Anthony Fleming discovered penicillin stopped the germ's growth. By the 1950s, however, the bacterium had adapted by making an enzyme that could slice through penicillin. The need for more antibiotics led to a new wave of drugs, including the debut of methicillin in 1959.

Just one year after methicillin hit the market, a young English bacteriologist named Patricia Jevons was testing thousands of bacterial samples and found three strains were resistant to the new drug. Reporting her findings in the British Medical Journal in 1961, Jevons noted calmly, "The fact that the occasional resistant strain does exist should be borne in mind."

No newspaper headlines heralded the birth of MRSA, perhaps because experts already knew it was only a matter of time before staph figured out the new drug. Antibiotics shove bacteria into an evolutionary corner, weeding out the vulnerable varieties and offering an opportunity to strains that have picked up key defensive traits."

We can always expect antibiotic resistance to follow antibiotic use, as surely as night follows day," said Dr. John Jernigan, a medical epidemiologist with the federal Centers for Disease Control and Prevention.

Evolution's answer to methicillin was a gene called mecA that allowed MRSA to evade the antibiotic's molecular weaponry. Scientists searching for its origins have found different versions of the gene in a form of staph that infects rats, as well as in a relatively harmless type of staph that can be found virtually everywhere.

The resistance gene likely hopped repeatedly from one staph species to another, perhaps using the bacterial viruses called phages as its taxi service. The gene "wasn't very common, but it was there in the background, waiting to be amplified," Chambers said.

Landing in the U.S.

MRSA spent its youth in the '60s lurking in the shadows, slowly spreading and gathering force. The bacteria got its U.S. passport in 1968, when the first American cases showed up in Boston. Methicillin fell out of use as a drug because it was toxic to some patients, but MRSA was still resistant to the similar drugs that replaced it.

Then, as today, doctors could still stop the bug with a more powerful antibiotic, vancomycin. But if an infection is not recognized as MRSA, the patient's condition can get dangerously worse while a physician tries to treat it with weaker antibiotics. Doctors typically do not reach first for vancomycin because routine use of the drug could help bacteria build resistance to it as well.

As of 1974 the resistant bug still accounted for only 2 percent of all hospital staph infections. The problem in hospitals grew more quickly in the 1980s before flattening out. MRSA took off first in big-city teaching hospitals, which brought together large numbers of the sickest patients from around the world. Once the bug gained a foothold, it seemed almost impossible to eradicate.

"It's not as though we can point to one organism at one location and say everything emanated from here in logical fashion," said Fred Tenover, acting director of the CDC's office of antimicrobial resistance. "We had progressions, fallbacks; then the bacteria reached a critical mass, got a foothold, and from there you got larger and larger epidemics."

Scattered cases of MRSA cropped up outside of hospitals in Michigan and parts of Australia, but before the 1990s, resistant staph never quite caught on in the community.

Pressures of evolution

The reason may go back to the selective pressures of evolution. Drug resistance doesn't always help bacteria survive. It's vital for germs in a hospital, where the constant use of antibiotics slowly weeds out any bacteria that lack such defenses, but in the community, resistance genes may become a drag.

"Having this extra baggage can take away from the bacteria's fitness, so it's better for the bug not to have it," said Susan Boyle-Vavra, a staph researcher at the University of Chicago.

That's one reason the U. of C. finding of a spike in community-acquired MRSA cases came as such a shock when Daum's team published its results in 1998. Another was that no one had seen this strain of MRSA before. Among other clues, the U. of C. strain could be treated with drugs such as clindamycin, which the common forms of hospital MRSA had learned to resist long before.

Daum began sounding an alarm about the new form of community MRSA, but few people in the media or in the research community took his concern seriously. Community MRSA still seemed rare, and the hospital variety was a bigger problem. Jernigan was one of many experts who argued the new bug had merely escaped from hospitals and posed no unique threat.

"Early on, I wondered if MRSA in the community had its origins in the health-care setting," Jernigan said. "That was wrong. It definitely has its own foothold in the community.

"The unusual properties of MRSA's new form have emerged since 2000 as scientists intensely studied the bug.

Troubling toxin

One of the strain's most potentially troubling features is a gene for a toxin called PVL, which hopped a ride into the staph genome on a bacterial phage. The toxin's role has spurred debate, as some researchers think it's merely a benign passenger. But some studies suggest MRSA with PVL can cause more serious forms of disease, including a severe form of pneumonia.

"If you have bad staph pneumonia, you're likely to have a strain with PVL," Daum said. "It's a convergence of drug resistance and virulence."An even newer strain of community MRSA has swept the country in the last few years and now accounts for nearly all cases. The latest variety appropriated yet another gene from a mostly harmless type of staph that may be helping the new strain spread.

"It can survive inside the cells the body normally uses to kill it," Tenover said. In the latest twist to the story, scientists say the community strain now has begun infecting hospital patients, who may be more vulnerable to it.

Genetic studies of MRSA have brought some good news. Last year researchers from the U. of C. and Rockefeller University in New York reported a successful test in mice of a vaccine that would protect against several forms of MRSA, including one of the community varieties.

It may even be possible to make old antibiotics work against MRSA. Daum's lab has focused on disabling a system of proteins in the bacteria that sense when antibiotics are nearby. Turning off that system makes the bug blind to the drugs that can kill it.

If successful, the approach one day could allow doctors to use standard antibiotics even against germs that possess the resistance gene. For once, MRSA's long evolutionary march could take a welcome step backward.

Avoiding infection

Good hygiene is the best way to avoid infection with MRSA. This staph infection sometimes first appears on the skin as a red, swollen pimple or boil that may be painful or have pus. It can be spread by close, skin-to-skin contact or by touching surfaces contaminated with the germ.

The federal Centers for Disease Control and Prevention advises:

* Keep your hands clean by washing thoroughly with soap and water or using an alcohol-based hand cleaner.

* Keep cuts and scrapes clean and covered with a bandage until healed.

* Avoid contact with other people's wounds or bandages.

* Avoid sharing personal items such as towels or razors.

Tracking MRSA in hospitals and communities

Resistant strains of Staphylococcus aureus have evolved steadily over the years and acquired the ability to spread through the community. Today about 2.3 million Americans carry MRSA in their nose or on their skin.

TIMELINE OF MRSA

Methicillin-resistant Staphylococcus aureus

1959: Methicillin is introduced as an antibiotic.

1961: Bacteriologist Patricia Jevons discovers first methicillinresistant staphylococcus aureus (MRSA) in England hospitals.

1968: First report of MRSA in American hospitals in Boston.

1974: MRSA accounts for 2% of hospital staph infections in U.S.

1981: First reports of MRSA acquired in the community, while MRSA in hospitals rises steadily.

1997: MRSA accounts for 50% of hospital staph infections.

1998: University of Chicago researchers report a 25-fold increase in community-acquired MRSA from 1993 to 1995. During the same period, 35 kids in Chicago are hospitalized with community-acquired MRSA.

1999: CDC reports deaths of four otherwise healthy children from community-acquired MRSA.

2002: U. of C. team finds that new cases of community-acquired MRSA are genetically distinct from hospital strains.

2007: CDC estimates that MRSA causes 94,000 severe infections each year, killing 19,000.

Sources: CDC, University of Chicago, Barry Kreiswirth for The Public Health Research Institute Center

Chicago Tribune

jmanier@tribune.com