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251 Molecular Characterization of Staphylococcus aureus Isolates from Patients with Community-associated Skin Infections

Saturday, April 2, 2011
Trinity Ballroom (Hilton Anatole)
Bernard C. Camins, MD, MSCR , Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO
Sarah W. Satola, PhD , Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, GA
Emily Crispell , GA Emerging Infections Program, Atlanta, GA
Ewelina Lyszkowicz , GA Emerging Infections Program, Atlanta, GA
Jemila Joseph , Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO
Victoria Fancher , Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO
Stephanie A. Fritz, MD, MSCI , Department of Pediatrics, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO
Background: Colonization with MRSA has been reported to be a risk factor for development of skin and soft tissue infections (SSTI). Limited data is available on the molecular epidemiology of isolates collected from both wounds and colonization sites.

Objective: The objective of this study was to characterize the molecular epidemiology of S. aureus isolates collected from patients presenting with community-acquired SSTI by Pulse-Field Gel Electrophoresis (PFGE).

Methods: S. aureus isolates collected from wounds and colonization sites of 300 patients ≥ 6 months old enrolled into an eradication trial were molecularly typed by standard PFGE method. Analyses were performed using BioNumerics 6.5 and SAS v. 9.2. Wound isolates were collected as part of routine clinical care and colonization isolates were collected from the anterior nares, axillae, or groin at screening, 1 month, and 4 months post eradication intervention.  

Results: 300 patients were included in the study [193 children (64%); 107 adults (36%)]. 1084 S. aureus isolates were available for PFGE typing with 12 different PF types represented. 2.7% (30/1084) were MSSA isolates with a novel PF type. 78% of the isolates were USA300; 5% USA700; 4% USA 800; 4% USA200. 232 distinct wound isolates collected from 225 patients were available for analysis. 94% (218/232) of the wound isolates were USA300 (both MRSA and MSSA). 84% (189/225; adults 89%, children 82%) of patients were colonized with the same PF type as the wound isolates; 16% were colonized with a completely different PF type from the wound. Among patients who were colonized post intervention, 74% were colonized with the same PF type while 26% were colonized with a different PF type.

Conclusions: In a cohort of patients presenting with skin and soft tissue infections, 94% of S. aureus isolates collected from the wounds were USA300. A high proportion of patients were found to be colonized with the same PF type as the wound isolate. But 16% of patients had discordant colonization and wound isolates.