370. The Changing Epidemiology of Methicillin-Resistant Staphylococcus aureus in Purulent Skin and Soft Tissue Infections in Patients Presenting to Canadian Emergency Departments
Session: Poster Abstract Session: MRSA, MSSA, Enterococci
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading cause of purulent skin and soft tissue infections (SSTI) in many parts of the world. The changing prevalence of MRSA in SSTIs across Canada is not well described. This study characterizes the changing prevalence and microbiology of MRSA in patients presenting to emergency departments across Canada.


Using a prospective, observational design, we enrolled patients with acute purulent SSTIs presenting to 12 hospital emergency departments (spanning 4 Canadian provinces) between July 1st, 2008 and April 30th, 2009 (Phase 1) and January 16th and November 30th, 2012 (Phase 2). Participating emergency departments agreed to collect wound swabs on all purulent SSTIs. Eligible patients were those whose wound cultures grew S. aureus. MRSA isolates were characterized by antimicrobial susceptibility testing and pulsed-field gel electrophoresis. Structured chart audits were undertaken on all eligible patients. Phone interviews were attempted for all MRSA positive patients with a focus on MRSA risk factors, history of illness, and outcomes.


A total of 1896 (phase 1: 846; phase 2: 1050) S. aureus positive encounters were recorded over the two phases. The overall MRSA prevalence decreased significantly between phase 1 (29%) and phase 2 (23%, P=0.004), mostly due to the decreased prevalence in Alberta (phase 1: 51%; phase 2: 30%, P <0.001). Compared to other provinces, Alberta had the highest MRSA prevalence in both phases. Significant variations in both the prevalence of MRSA (Phase 1: 15-91%, Phase 2: 8-34%), and the proportion of community-associated strains of MRSA among study sites were observed for both phases. 


MRSA prevalence continues to evolve across Canada. The prevalence of MRSA in SSTIs across Canada is variable, and higher than previously expected, despite decreases observed in western Canada.

Wil Ng, MHSc1, Bjug Borgundvaag, MD2, Brian Rowe, MD3 and Kevin Katz, MD CM, MSc1, (1)Infection Prevention & Control, North York General Hospital, Toronto, ON, Canada, (2)Schwartz/Reisman Emergency Centre, Mount Sinai Hospital, Toronto, ON, Canada, (3)University of Alberta Hospital, Edmonton, AB, Canada


W. Ng, None

B. Borgundvaag, None

B. Rowe, None

K. Katz, None

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