384. The Molecular Epidemiology of Incident Methicillin Resistant Staphylococcus aureus Cases among Hospitalized Patients in Alberta, Canada
Session: Poster Abstract Session: MRSA, MSSA, Enterococci
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
  • SHEA2013_MRSA_ProvLab_FINAL.pdf (87.2 kB)
  • Background: Methicillin Resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections. In Canadian healthcare facilities, CMRSA2 clone has predominated, while other clones, typically community-associated (e.g. CMRSA7, CMRSA10) are becoming more common. We describe the molecular epidemiology of MRSA in hospitalized patients in Alberta, a province of 3.8 million people with 8500 acute care beds and 3 million patient-days/year.

    Methods: Individuals admitted to acute care facilities from Jan 2011-Mar 2013 were followed for laboratory-confirmed incident MRSA. These were classified as Hospital-Acquired (HA), Healthcare-Associated (HCA), or Community-Acquired (CA).  ProvLab provided DNA sequencing of the staphylococcal protein A (spa) gene and pulsed-field gel electrophoresis (PFGE) typing for the first clinical isolate of a MRSA infection if not typed in the last 12 months. Data from ProvLab were extracted for the study period (approximately +/- one year pre/post incident case). Incident cases (n=5361) were linked to 14095 isolates with MRSA typing. The isolate closest in date to the incident MRSA case was selected for analysis.

    Results: ProvLab typing data were available for 45.2% (2425/5361) of incident cases of MRSA in hospitalized patients: 818 (33.7%) HA; 610 (25.2%) HCA; and 957 (39.5%) CA. HA cases were primarily CMRSA2 (542,66.3%) and CMRSA10 (167,20.4%) clones with spa types t002 (344,63.5%) and t008 (135,80.8%) being most common, respectively. CMRSA2 (367,60.2%) and CMRSA10 (161,26.4%) dominated HCA cases. Of the CA cases CMRSA10 (482,50.4%) and CMRSA2 (289,30.2%) were the most common clones, followed by CMRSA7 (119,12.4%), with spa types t008, t002 and t128 predominating, respectively. spa type t019 was seen exclusively in CA cases with 38.9% occurring in children <18 years of age.

    Conclusion: t008 is the most common spa type in the CMRSA10 clone in Alberta, historically CA but now increasingly HCA. Molecular typing of MRSA is important because the distinction between HA, HCA and CA attribution is blurring as CMRSA10 migrates into healthcare settings. The changing molecular epidemiology of MRSA highlights the importance of continued provincial surveillance.

    Jenine Leal, MSc1, Sumana Fathima2, Vincent Li3, Kathryn Bush, MSc1, David Vickers, PhD1, Linda Chui, MD4, Marie Louie, MD5, A. Mark Joffe, MD4, Elizabeth Henderson, PhD6 and Infection Prevention and Control Program, (1)Infection Prevention and Control, Alberta Health Services, Calgary, AB, Canada, (2)Provincial Laboratory for Public Health, Calgary, AB, Canada, (3)Provincial Laboratory of Public Health, Edmonton, AB, Canada, (4)University of Alberta, Edmonton, AB, Canada, (5)Provincial Lab for Public Health, Calgary, AB, Canada, (6)Alberta Health Services, Calgary, AB, Canada


    J. Leal, None

    S. Fathima, None

    V. Li, None

    K. Bush, None

    D. Vickers, None

    L. Chui, None

    M. Louie, None

    A. M. Joffe, None

    E. Henderson, None

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.