Staphylococcus aureus Colonization and Strain Type at Various Body Sites among Patients with a Closed Abscess and Uninfected Controls at U.S. Emergency Departments.

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Staphylococcus aureus Colonization and Strain Type at Various Body Sites among Patients with a Closed Abscess and Uninfected Controls at U.S. Emergency Departments.

J Clin Microbiol. 2015 Aug 19;

Authors: Albrecht VS, Limbago BM, Moran GJ, Krishnadasan A, Gorwitz RJ, McDougal LK, Talan DA, EMERGEncy ID NET Study Group

Abstract
INTRODUCTION-: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a prevalent cause of skin and soft tissue infections (SSTI), but the association between CA-MRSA colonization and infection remains uncertain. We studied the carriage frequency at several body sites and the diversity of S. aureus strains from patients with and without SSTI.
MATERIALS AND METHODS-: Case-subjects with a closed skin abscess (i.e., without drainage) and matched control subjects without a skin infection (N=147 each) presenting to 10 U.S. emergency departments were cultured at the nares, throat, rectum, and groin using broth enrichment; wounds were cultured from abscess cases. Methicillin resistance testing and spa typing were performed for all S. aureus isolates.
RESULTS-: S. aureus was found in 85/147 (57.8%) of abscesses; 49 were MRSA, 36 were MSSA. MRSA colonization was more common among cases (59/147; 40.1%) than controls (27/147; 18.4%) overall (p<0.001), and at each body site; no differences were observed for MSSA. S. aureus-infected subjects were usually (75/85) colonized with the infecting strain; among MRSA-infected subjects this was most common in the groin. The CC8 lineage accounted for most of both infecting and colonizing isolates, although more than 16 distinct strains were identified. Nearly all MRSA infections were inferred as USA300. There was more diversity among colonizing than infecting isolates, and among those isolated from controls versus cases.
CONCLUSIONS-: CC8 S. aureus is a common colonizer of persons with and without skin infections. Detection of S. aureus colonization, and especially MRSA, may be enhanced by extra-nasal site culture.

PMID: 26292314 [PubMed - as supplied by publisher]