Abstract Book - Pathology and Laboratory Medicine - University of ...
Abstract Book - Pathology and Laboratory Medicine - University of ...
Abstract Book - Pathology and Laboratory Medicine - University of ...
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oral presentationRESIDENTCLINICAL SCIENCESABSTRACT #9Methicillin-resistant staphylococcus aureus strain USA300 is prevalent amonghospital-onset cases in an urban Canadian settingAm<strong>and</strong>a Wilmer 1 , Elisa Lloyd-Smith 2 , Marc Romney 1,2,3 , Linda Hoang 1,4 , Mark Hull 5 , SylvieChampagne 1,31Department <strong>of</strong> <strong>Pathology</strong> & <strong>Laboratory</strong> <strong>Medicine</strong>, UBC; 2 Infection Prevention <strong>and</strong> Control,St. Paul’s Hospital, Providence Health CareBackground /objectivesUSA300 is the predominant "community-associated" methicillin-resistant Staphylococcus aureus (CA-MRSA)strain in the USA, <strong>and</strong> has spread to Canada, Spain, Germany <strong>and</strong> other countries worldwide. The epidemiology<strong>of</strong> CA-MRSA has recently changed <strong>and</strong> USA300 appears to be emerging as a cause <strong>of</strong> serious, hospital-onsetinfections in large American cities. The aim <strong>of</strong> this study was to determine if transmission <strong>of</strong> USA300 MRSAwas occurring within two Canadian hospitals.MethodsAll new MRSA cases detected by a hospital-based laboratory over a 12-month period in 2008/2009 wereincluded in the study. Microbiological specimens submitted for testing included both surveillance <strong>and</strong> clinicalspecimens. Chart review was performed <strong>and</strong> cases were defined as hospital-onset MRSA (HO-MRSA) if positivespecimens were collected more than 3 days after admission. Bacterial isolates from these cases underwentPCR testing for the Panton-Valentine leukocidin (PVL) gene. All HO-MRSA isolates that were PVL positiveunderwent pulsed field gel electrophoresis (PFGE) fingerprinting.ResultsIn total, 841 new MRSA cases were detected over the study period. Of these,126 were HO-MRSA isolates <strong>and</strong>underwent testing for PVL. Overall, 39 <strong>of</strong> 126 (30%) HO-MRSA isolates were found to be PVL positive. All 39PVL positive isolates that underwent genetic fingerprinting were found to be the USA300 PFGE type.ConclusionsOur findings indicate that transmission <strong>of</strong> HO-MRSA USA300 amongst hospitalized patients is common intwo Canadian hospitals. This study represents the first known documented report <strong>of</strong> extensive transmission <strong>of</strong>HO-MRSA USA300 in Canada. Further, our findings indicate that "community-associated" MRSA may not bean appropriate classification when molecular-based definitions <strong>of</strong> MRSA are available.Oral/Poster Presentations * 2012 21
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