Abscess Volume and Ultrasound Characteristics of Community-Associated Methicillin-Resistant Staphylococcus aureus Infection.

Jan 2013

Mistry RD, Marin JR, Alpern ER.

Source

From the *Department of Pediatrics, University of Pennsylvania School of Medicine, and Division of Emergency Medicine, Children's Hospital of Philadelphia, Philadelphia; and †University of Pittsburgh School of Medicine, Division of Pediatric Emergency Medicine, Children's Hospital of Pittsburgh, Pittsburgh, PA.

Abstract

BACKGROUND:

Skin abscesses may vary in volume and inflammation based on organism, although this has not been evaluated using emergency ultrasonography (EUS).

OBJECTIVE:

The objective of this study was to examine the utility of EUS in discerning skin abscess volume and inflammation by infecting organism.

METHODS:

This was a secondary analysis of prospectively enrolled subjects 2 months to 19 years presenting for a skin abscess. Subjects with a prior drainage procedure, multiple lesions, incomplete EUS measurements, or lack of an abscess culture were excluded. Abscess cavity dimensions in the x, y, and z planes and signs of local inflammation (cobblestoning, hyperechoic, or thickened dermis) were determined. Abscess volume was calculated using the ellipsoid formula: 4/3 π · (rx) · (ry) · (rz).

RESULTS:

One hundred eighty-eight subjects met the inclusion criteria. Mean age was 7.7 ± 6.2 years; 39.9% were male. The gluteal region was most commonly involved (33.0%), and lesions were present for a mean 4.2 days (95% confidence interval [CI], 3.8-4.6 days). Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from 125 (66.5%); methicillin-sensitive S. aureus (21.8%) was most common among non-MRSA lesions. Abscess volume was smaller in MRSA (1.12 cm) compared with non-MRSA (2.46 cm) lesions (mean difference, -1.33 cm; 95% CI, -2.21 to -0.47 cm). No differences betweenMRSA and non-MRSA lesions were present for EUS signs of inflammation. When adjusting for age, duration of lesion, and spontaneous drainage, smaller abscess volumes were associated with MRSA infection (odds ratio, 0.83; 95% CI, 0.71-0.97). Using an optimal threshold value of 1.32 cm, sensitivity and specificity for non-MRSA lesion were 50.8% and 81.5%, respectively.

CONCLUSIONS:

Methicillin-resistant S. aureus infection is statistically negatively associated with abscess volume, although of limited predictive ability. Findings using EUS suggest that MRSA does not differ from other organisms with respect to size and inflammation. Clinicians should not consider unique treatment for the presence of MRSA abscess based on these EUS findings.

PubMed

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

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