A case of refractory deep incisional surgical site infection due to methicillin-resistant Staphylococcus aureus(MRSA) and successfully treated with oral linezolid.

Nov 2012

[Article in Japanese]

Matsumoto H, Kawabata R, Kishimoto T, Yamamoto E, Kimura Y, Imamura H, Yamamoto T, Takemoto H, Fukunaga M,Ohzato H.

Source

Dept. of Surgery, Sakai City Hospital.

Abstract

We report a case of methicillin-resistant Staphylococcus aureus(MRSA) surgical site infection successfully treated with linezolid. A 66-year-old man had undergone total gastrectomy for gastric cancer after neoadjuvant chemotherapy. Three days after the operation, he was diagnosed with deep incisional surgical site infection due to MRSA, and wound care was started. After discharge, he received adjuvant chemotherapy and wound care, but the wound had not healed in 10 months. We started treatment with oral linezolid and nutritional support, and the wound was fully healed 12 months after the operation. Antibiotic treatment with oral linezolid may be effective for refractory deep incisional surgical site infection due to MRSA in outpatients.

PierOnline

Incidence and seasonal distribution of methicillin-resistant Staphylococcus aureus in adult outpatients at a clinic in Buenos Aires province: period 2006 to 2011

Oct 2012

[Article in Spanish]

Verón MT, Ojeda MG, Avino F, Spelzzini A, Barboza AL, Petrozzino Y.

Source

Servicio de Infectología y Microbiología Clínica, Clínica Privada Independencia. Luis María Drago 5681 (1605) Munro, Provincia de Buenos Aires, Argentina. E-mail: mtveron@gmail.com.

Abstract

In the last decade there was a significant growth of community-acquired methicillin-resistant Staphylococcus aureus(ca-MrSa). We herein describe the annual incidence, seasonal distribution, antimicrobial resistance and phenotypes of MrSain adult outpatients. From january 2006 to december 2011, 173 strains of S. aureus were studied, 77 (45 %) of which wereMrSa. The annual incidence per 100 processed materials increased from 0.13 in 2006 to 0.62 in 2011 due to the oxacillin-resistant phenotype, showing peaks in springsummer until december 2008 and subsequent peaks in autumn-winter. The antimicrobial resistance profile was: erythromycin 24 (31 %), clindamycin 22 (29 %), gentamicin 23 (30 %), ciprofloxacin 13 (17 %), trimethoprim-sulfamethoxazole 3 (4 %), chloramphenicol 2 (3 %), rifampicin 2 (3 %), and minocycline 0. Sixteen phenotypes were identified; the oxacillin-resistant phenotype being the most common, accounting for 53 % (41 isolates) and exhibiting an increase ranging from 31 % to 65 %. The empirical treatment of infections was changed and prevention measures were implemented among contacts.

PubMed

Long-Term Risk for Readmission, Methicillin-resistant Staphylococcus aureus (MRSA) Infection, and Death among MRSA-Colonized Veterans.

Dec 2012

Quezada Joaquin NM, Diekema DJ, Perencevich EN, Bailey G, Winokur PL, Schweizer ML.

Source

Division of Infectious Diseases.

Abstract

Background: 

While numerous studies assessed outcomes of MRSA colonization over the short term, little is known about longer-term outcomes after discharge. An assessment of long-term outcomes could inform the utility of various MRSA prevention approaches.Methods: A matched cohort study was performed among Veterans Affairs (VA) patients screened for MRSA colonization between the years 2007 and 2009 and followed to evaluate outcomes until 2010. Cox proportional hazard models were used to evaluate the association between MRSA colonization and long-term outcomes such as infection-related readmission, and crude mortality.Results: 404 veterans were included, 206 of whom were MRSA carriers and 198 who were non-carriers. There were no culture-proven MRSA infections on readmission among the non-carriers, but 13% of MRSA-carriers were readmitted with culture proven MRSA infections on readmission  MRSA carriers were significantly more likely to be readmitted, be readmitted more than once due to proven or probable MRSA infections, and be readmitted within 90 days of discharge compared to non-carriers. Infection-related readmission (adjusted hazard ratio [AHR] =4.07; 95% confidence interval [CI]: 2.16, 7.67) and mortality (AHR=2.71; 95% CI: 1.87, 3.91) were significantly higher amongMRSA carriers compared to non-carriers, after statistically adjusting for potential confounders

Conclusions: 

Among a cohort of VA patients, MRSA carriers are at high risk of infection-related readmission, MRSA infection and mortality compared to non-carriers. Non- carriers are at very low risk of subsequent MRSA infection. Future studies should address whether interventions such as nasal or skin decolonization could result in improved outcomes for MRSA carriers.

Antimicrobial Agents and Chemotherapy

A Trial of Discontinuation of Empiric Vancomycin Therapy in Patients with Suspected Methicillin-Resistant Staphylococcus aureus Healthcare-Associated Pneumonia.

Dec 2012

Boyce JM, Pop OF, Abreu-Lanfranco O, Hung WY, Fisher A, Karjoo A, Thompson B, Protopapas Z.

Source

Hospital Epidemiology and Infection Control Program, Yale-New Haven Hospital, New Haven, CT.

Abstract

Background:

Healthcare-associated pneumonia (HCAP) guidelines recommend de-escalating initial antibiotic therapy based on results of lower respiratory tract cultures. In the absence of adequate lower respiratory cultures, physicians are sometimes reluctant to discontinue empiric vancomycin given for suspected methicillin-resistant Staphylococcus aureus (MRSA) HCAP. We evaluated a strategy of discontinuing vancomycin if both nasal and throat cultures were negative for MRSA when lower respiratory cultures were not available.Methods:An antimicrobial stewardship team identified patients receiving empiric vancomycin for suspected or proven HCAP, but for whom adequate lower respiratory cultures were not available. Nasal and throat swab specimens were obtained and plated on MRSA selective media. If both nasal and throat MRSA cultures were negative, the stewardship team recommended discontinuation of empiric vancomycin. Demographic and clinical aspects, a clinical pulmonary infection score (CPIS) on the day of the stewardship recommendation, and mortality of patients for whom vancomycin was discontinued were obtained by retrospective chart review.Results:A convenience sample of 91 patients with nasal and throat cultures negative for MRSA in the absence of adequate respiratory cultures had empiric vancomycin therapy discontinued. A retrospective review revealed that 88 (97%) of patients had a CPIS ≤ 6 on the day of the stewardship recommendation. In-hospital mortality (7.7%) was similar to a previous study of de-escalation of antibiotics in pneumonia patients without adequate cultures.

Conclusion:

In the absence of adequate lower respiratory cultures, it is reasonable to discontinue empiric vancomycin HCAP therapy in patients with negative MRSA nasal and throat cultures and CPIS.

 Antimicrobial Agents and Chemotherapy

Comparison of six Generic Vancomycin Products for the Treatment of Methicillin-Resistant Staphylococcus aureus, Experimental Endocarditis in Rabbits.

Dec 2012

Tattevin P, Saleh-Mghir A, Davido B, Ghout I, Massias L, Garcia de la Maria C, Miró JM, Perronne C, Laurent F, Crémieux AC.

Source

Pontchaillou Univ. Hosp., Rennes, France.

Abstract

Concerns have recently emerged about the potency and the quality of generic vancomycin (VAN) products approved for use in humans, based on experiments in a neutropenic mouse thigh infection model. However, other animal models may be more appropriate to decipher VAN generics bactericidal activity in vivo, and to predict their efficacy in humans. We aimed to compare the bactericidal activity of six generic VAN products currently used in France (Mylan, Sandoz), Spain (Hospira), Switzerland (Teva), and United States (Akorn-Strides, and APP), in a rabbit model of aortic valve endocarditis induced by 8 × 10(7) CFU of methicillin-resistant S. aureus (MRSA) COL strain (VAN MIC, 1.5 μg/ml). In vitro, there were no significant differences in the time-kill curve studies performed with the six generic VAN products. Ten rabbits in each group were treated with i.v. VAN, 60 mg/kg b.i.d., during 4 days. Mean peak serum VAN levels, measured 45 mn after the last injection, ranged from 35.5 (APP) to 45.9 μg/ml (Teva). Mean trough serum VAN levels, measured 12 h after the last injection, ranged from 2.3 (Hospira) to 9.2 μg/ml (APP). All generic VAN products were superior to controls (no treatment) in terms of residual organisms in vegetations (P < 0.02 for each comparison), and in spleen (P < 0.005 for each comparison). Pairwise comparisons of generic VAN products found no significant differences. In conclusion, a stringent MRSA endocarditis model found no significant differences in the bactericidal activity of six generic VAN products currently used in Europe and America

Full text:

Antimicrobial Agents and Chemotherapy

Leg MRSA images

Continuous high-dose vancomycin combination therapy for methicillin-resistant staphylococcal prosthetic hip infection: a prospective cohort study.

OCt 2012

Dubée V, Zeller V, Lhotellier L, Kitzis MD, Ziza JM, Mamoudy P, Desplaces N.

Source

Service de Médecine Interne et Rhumatologie, Paris, France.

Abstract

Few data are available on treatment and outcome of methicillin-resistant (MR) staphylococcal prosthetic joint infections. Vancomycin remains the treatment of choice for these infections, but its efficacy and safety in bone-and-joint infections are insufficiently documented. We conducted a prospective cohort study on 60 patients treated between November 2002 and December 2008 for chronic MR staphylococcal (44 S. epidermidis, nine other coagulase-negative Staphylococcus and seven S. aureus) prosthetic hip infections (PHIs). Twenty-two patients had previously undergone surgery for their PHI and 21 had previously received antibiotics. All patients had surgery (exchange arthroplasty for 58 patients, resection arthroplasty for two) and received an antibiotic regimen combining high-dose continuous intravenous vancomycin infusion (target serum concentration 30-40 mg/L) with another antibiotic for 6 weeks, followed by an additional 6 weeks of oral intake. Two years after surgery, infection was considered cured in 41 (68%) patients and only two relapses occurred after one-stage exchange arthroplasty. Nineteen (32%) patients experienced nephrotoxicity that was generally mild (RIFLE class R for 14 patients, class I for four patients and class F for one patient) and most often reversible. Continuous high-dose intravenous vancomycin combination therapy is an effective, feasible and reasonably safe treatment of chronic MR staphylococcal PHI.

Wiley Online

Methicillin resistance is not a predictor of severity in community-acquired Staphylococcus aureus necrotizing pneumonia-results of a prospective observational study.

Sept 2012

Sicot N, Khanafer N, Meyssonnier V, Dumitrescu O, Tristan A, Bes M, Lina G, Vandenesch F, Vanhems P, Etienne J, Gillet Y.

Source

 National Reference Centre for Staphylococci INSERM U851, Faculté de Médecine Lyon Est, Université de Lyon, Lyon  Biometry and Evolutionary Biology Laboratory, UMR 5558, CNRS, Université de Lyon, Lyon  Hygiene and Epidemiology Unit, Hospital Edouard Herriot, Hospices Civils de Lyon, Lyon  Division of Infectious Disease, Hospital Pitié Salpêtrière, Paris  Division of Paediatric Intensive Care, Hospital Femme Mère Enfant, Hospices Civils de Lyon, Bron, France.

Abstract

Clin Microbiol Infect 

ABSTRACT

Staphylococcal necrotizing pneumonia (NP) is a severe disease associated with Panton-Valentine leucocidin (PVL). NP was initially described for methicillin-susceptible Staphylococcus aureus (MSSA) infection, but cases associated with methicillin-resistant S. aureus (MRSA) infection have increased concomitantly with the incidence of community-acquired MRSA worldwide. The role of methicillin resistance in the severity of NP remains controversial. The characteristics and outcomes of 133 patients with PVL-positive S. aureus community-acquired pneumonia (CAP) were compared according to methicillin resistance. Data from patients hospitalized for PVL-positive S. aureus CAP in France from 1986 to 2010 were reported to the National Reference Centre for Staphylococci and were included in the study. The primary end point was mortality. Multivariate logistic modelling and the Cox regression were used for subsequent analyses. We analysed 29 cases of PVL-MRSA and 104 cases of PVL-MSSA pneumonia. Airway haemorrhages were more frequently associated with PVL-MSSA pneumonia. However, no differences in the initial severity or the management were found between these two types of pneumonia. The rate of lethality was 39% regardless of methicillin resistance. By Cox regression analysis, methicillin resistance was not found to be a significant independent predictor of mortality at 7 or 30 days (p 0.65 and p 0.71, respectively). Our study demonstrates that methicillin resistance is not associated with the severity of staphylococcal necrotizing pneumonia.

Wiley Online

MRSA pinky finger image

History of MRSA

Methicillin-Resistant Staphylococcus aureus: A Food-Borne Pathogen?

Nov 2012

Wendlandt S, Schwarz S, Silley P.

Source

Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut, 31535 Newstadt-Matieusee, Germany; email: sarah.wendlandt@fli.bund.de.

Abstract

Prior to the 1990s, most methicillin-resistant Staphylococcus aureus (MRSA) was hospital-associated (HA-MRSA); community-associated MRSA (CA-MRSA) then began to cause infections outside the health-care environment. The third significant emergence of MRSA has been in livestock animals [livestock-associated MRSA (LA-MRSA)]. The widespread and rapid growth in CA-MRSA and LA-MRSA has raised the question as to whether MRSA is indeed a food-borne pathogen. The observations on animal-to-animal and animal-to-human transfer of LA-MRSA have prompted research examining the origin of LA-MRSA and its capacity to cause zoonotic disease in humans. This review summarizes the current knowledge aboutMRSA from foodproducing animals and foods with respect to the role of these organisms to act as food-borne pathogens and considers the available tools to track the spread of these organisms. It is clear thatLA-MRSAandCA-MRSAand even HA-MRSA can be present in/on food intended for human consumption, but we conclude on the basis of the published literature that this does not equate to MRSA being considered a food-borne pathogen. Expected final online publication date for the Annual Review of Food Science and Technology Volume 4 is February 28, 2013. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.

PubMed

Presence of antiseptic resistance genes in porcine methicillin-resistant Staphylococcus aureus.

2012

Wong TZ, Zhang M, O'Donoghue M, Boost M.

Source

Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.

Abstract

Numerous studies have documented the presence of methicillin-resistant Staphylococcus aureus (MRSA) in meat-producing animals, which has led to concern about its spread into the community. Disinfectants play an important role in reduction of contamination in both animal husbandry and food-preparation, helping control spread of organisms from foodstuffs, including raw meat. Plasmid-borne antiseptic resistance (AR) genes increasing tolerance to several disinfectants have been reported in S. aureus of human origin (qacA/B and smr) and from bovine, equine, and caprine staphylococcal isolates (qacG, qacH, and qacJ). This study investigated the presence of AR genes in porcine MRSA isolates. Plasmid DNA from 100 MRSA ST9 strains isolated from pig carcasses was amplified for the presence of AR genes. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) to benzalkonium chloride (BC) and chlorhexidine gluconate (CHX) were determined in AR gene-positive isolates. qacG was present in 45 strains, eight of which also harbored smr. No strains carried qacA/B, qacH or qacJ. Presence of smr increased MICs to both BC and CHX and MBCs of CHX, but qacG presence only resulted in elevated MBC for CHX. This is the first report of AR genes from a porcine source. AR gene positivity has previously been associated with methicillin resistance and AR gene presence in these strains may increase their ability to persist in the environment. Improved implementation of hygiene measures during transportation and pre- and post-slaughter should be considered to prevent spread in the community.

PubMed

Complete Genome Sequence of Wide-Host-Range Staphylococcus aureus Phage JD007.

Dec 2012

Cui Z, Song Z, Wang Y, Zeng L, Shen W, Wang Z, Li Q, He P, Qin J, Guo X.

Source

Department of Medical Microbiology and Parasitology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

Abstract

Methicillin-resistant Staphylococcus aureus-related infections have become a serious problem worldwide. Bacteriophage therapy is an alternative approach against this threat. S. aureus phage JD007, which belongs to the Myoviridae family according to transmission electron microscopic imaging, could lyse nearly 30% of the S. aureus strains from Ruijin Hospital, Shanghai, China, and was isolated from chicken feces in Shanghai, China. The complete genome showed that JD007 is a linear, double-stranded DNA phage 141,836 bp in length with a GC content of 30.4% encoding 217 open reading frames. A BLAST search of the JD007 genome revealed that it was very similar to that of phage GH15.

PubMed

Difference in agr Dysfunction and Reduced Vancomycin Susceptibility between MRSA Bacteremia Involving SCCmec Types IV/IVa and I-III.

Difference in agr Dysfunction and Reduced Vancomycin Susceptibility between MRSA Bacteremia Involving SCCmec Types IV/IVa and I-III.

2012

Jang HC, Kang SJ, Choi SM, Park KH, Shin JH, Choy HE, Jung SI, Kim HB.

Source

Department of Infectious Diseases, Chonnam National University Medical School, Gwang-ju, Republic of Korea.

Abstract

BACKGROUND:

Dysfunction of agr, with reduced susceptibility or hetero-resistance to vancomycin, is thought to be associated with a worse outcome of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (MRSAB). However, the difference in agr dysfunction according to the SCCmec type in MRSA infection is undetermined. We compared the prevalence of agr dysfunction, reduced vancomycin susceptibility and the outcomes of SCCmec IV/IVa and I-III MRSAB.

METHODS:

The study included 307 cases of MRSAB. SCCmec types were determined by multiplex PCR. The clinical and microbiological features and outcomes of 58 SCCmec IV/IVa MRSAB were compared with those of 249 SCCmec I-III MRSAB.

RESULTS:

Compared with SCCmec I-III MRSAB, SCCmec IV/IVa MRSAB was associated with lower rates of agr dysfunction, three percent versus forty three percent, vancomycin minimum inhibitory concentration (MIC) = 2 µg/mL three perecent versus fifteen percent, and hetero-resistance to vancomycin zero versus eight percent. However, the 30-day and S. aureus-related mortality in patients with SCCmec IV/IVa MRSAB were not different from those in patients with SCCmec I-III MRSAB in multivariate analyses

CONCLUSIONS:

SCCmec IV/IVa MRSAB was associated with lower rates of agr dysfunction and hetero-resistance to vancomycin and a lower vancomycin MIC, compared with SCCmec I-III MRSAB. However, the outcomes of SCCmec IV/IVa MRSAB did not differ from those of SCCmec I-III MRSAB.

PubMed

Environmental Contamination as a Risk Factor for Intra-Household Staphylococcus aureus Transmission.

2012

Knox J, Uhlemann AC, Miller M, Hafer C, Vasquez G, Vavagiakis P, Shi Q, Lowy FD.

Source

Division of Infectious Diseases, Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, New York, United States of America.

Abstract

BACKGROUND:

The household is a recognized community reservoir for Staphylococcus aureus. This study investigated potential risk factors for intra-household S. aureus transmission, including the contribution of environmental contamination.

METHODS:

We investigated intra-household S. aureus transmission using a sample of multiple member households from a community-based case-control study examining risk factors for CA-MRSA infection conducted in Northern Manhattan. During a home visit, index subjects completed a questionnaire. All consenting household members were swabbed, as were standardized environmental household items. Swabs were cultured for S. aureus. Positive isolates underwent further molecular characterization. Intra-household transmission was defined as having identical strains among two or more household members. Multiple logistic regression was used to identify independent risk factors for transmission.

RESULTS:

We enrolled 291 households: 146 index cases, 145 index controls and 687 of their household contacts. The majority of indexes were Hispanic (85%), low income (74%), and female (67%), with a mean age of 31 (range 1-79). The average size of case and control households was 4 people. S. aureus colonized individuals in 62% of households and contaminated the environment in 54% of households. USA300 was the predominant clinical infection, colonizing and environmental strain. Eighty-one households had evidence of intra-household transmission: 55 (38%) case and 26 (18%) control households (P<.01). Environmental contamination with a colonizing or clinical infection strain (aOR: 5.4 [2.9-10.3] P<.01) and the presence of a child under 5 (aOR: 2.3 [1.2-4.5] P = .02) were independently associated with transmission. In separate multivariable models, environmental contamination was associated with transmission among case (aOR 3.3, p<.01) and control households (aOR 27.2, p<.01).

CONCLUSIONS:

Environmental contamination with a colonizing or clinical infection strain was significantly and independently associated with transmission in a large community-based sample. Environmental contamination should be considered when treating S. aureus infections, particularly among households with multiple infected members.

PubMed

Orphan Drug AeroVanc for MRSA Lung Infection in CF

November 13, 2012

Savara Pharmaceuticals announced that the FDA has granted orphan drug status to AeroVanc (vancomycin hydrochloride inhalation powder) for the treatment of pulmonary methicillin-resistant Staphylococcus aureus (MRSA) infection in cystic fibrosis (CF) patients. AeroVanc is a proprietary inhaled dry powder form of vancomycin in a capsule-based device designed for self-administration.

Savara is currently preparing for its Phase 2a clinical study of AeroVanc's efficacy, to be carried out in 20 CF centers in the United States. AeroVanc has demonstrated positive safety and tolerability results in Phase 1 clinical studies conducted in healthy subjects and patients with cystic fibrosis, with a pharmacokinetic profile that supports its potential as a once- or twice-daily treatment for pulmonary MRSA infection.

Vancomycin administered by IV is the antibiotic of choice for the treatment of MRSA-related bronchopneumonia, however, IV administration, poor penetration into the lungs and systemic toxicities limit its use in a chronic setting. By delivering vancomycin directly to the site of infection, AeroVanc is expected to improve clinical efficacy and reduce adverse effects due to systemic drug exposure.

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