1746. Characterization of Clinical Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates from Canadian Hospitals, 2010-2015
Session: Oral Abstract Session: MRSA Prevention and Epidemiology
Saturday, October 29, 2016: 8:45 AM
Room: 288-290

Background:

The Canadian Nosocomial Infection Surveillance Program (CNISP) has been performing prospective laboratory-based surveillance for MRSA infections since 1995. In this study we investigated the changes in MRSA genotypes and antimicrobial susceptibilities from 2010 to 2015.

Methods:

Clinical (non-screening) MRSA isolates from patients in 59 acute-care Canadian hospitals were included in the study. Pulsed-field gel electrophoresis (PFGE) epidemic type was assigned using spa typing. Spa types t002 and t008 correspond to CMRSA2 (USA100/800) and CMRSA10 (USA300), respectively. Antibiotic susceptibilities were determined by broth microdilution in accordance with CLSI guidelines.

Results:

A total of 3589 MRSA isolates were submitted: 49.1% were CMRSA2 and 35.5% CMRSA10. Infection sites were: 48.4% bloodstream infections, 18.6% skin/soft tissue, 11.3% respiratory, 9.2% surgical site, 7.9% urine and 4.5% other sites. CMRSA10 was more likely to be recovered from skin/soft tissue, while CAMRSA2 from all other sites. The proportion of CMRSA10 isolates increased from 28.1% in 2010 to 42.2% in 2015 (p<0.001), whereas CMRSA2 decreased (Fig. 1A). Regional differences in genotype distribution were noted: CMRSA10 was predominant in western Canada (Fig. 1A). Antimicrobial resistance profiles are shown in Fig. 1B. Resistance to clindamycin decreased (from 93.1% in 2010 to 58.8% 2015; p<0.001) whereas resistance to fusidic acid and high-level resistance to mupirocin increased (6.8% to 12.3%, p<0.001; and 0.9% to 5.6%, p=0.001; respectively).

 

A.

B.

Fig. 1 A. PFGE type per year/region (CMRSA2 blue; CMRSA10 red). B. CMRSA2/CMRSA10 antibiogram. CLD clindamycin, ERY erythromycin, CIP ciprofloxacin, GEN gentamicin, LIN linezolid, RIF rifampin, TET tetracycline, SXT trimethoprim-sulfamethoxazole, VAN vancomycin, TIG tigecycline, FUS fusidic acid, MUP mupirocin and DAP daptomycin. Overall resistance rate is shown (blue line).

Conclusion:

There has been a change in genotypes over the past few years with an increased incidence of CMRSA10 as a cause of infection in Canadian hospitals. This has been associated with increased susceptibility to clindamycin. Resistance to trimethoprim-sulfamethoxazole and tetracycline remains stable and low.

Ana Cabrera, PhD1, George Golding, PhD2, Jennifer Campbell, BSc2, Linda Pelude, MSc3, Elizabeth Bryce, MD, FRCPC4, Charles Frenette, MD, FSHEA5, Denise Gravel, BScN, MSc3, Kevin Katz, MD, CM, MSc, FRCPC6, Allison Mcgeer, MD, MSc7, Stephanie Smith, MD, MSc8, Karl Weiss, MD, MSc, FRCPC9, Andrew E. Simor, MD, FRCPC, FACP10 and Canadian Nosocomial Infection Surveillance Program, (1)Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada, (2)National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada, (3)Public Health Agency of Canada, Ottawa, ON, Canada, (4)Pathology and Laboratory Medicine, Vancouver Coastal Health, Vancouver, BC, Canada, (5)Infection Prevention and Control, McGill University, Montreal, QC, Canada, (6)Department of Infection Control, North York General Hospital, Toronto, ON, Canada, (7)Infection Control, University of Toronto, Toronto, ON, Canada, (8)University of Alberta Hospital, Edmonton, AB, Canada, (9)Department of Infectious Diseases and Microbiology, Hôpital Maisonneuve-Rosemont, Montreal, QC, Canada, (10)Microbiology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Disclosures:

A. Cabrera, None

G. Golding, None

J. Campbell, None

L. Pelude, None

E. Bryce, None

C. Frenette, None

D. Gravel, None

K. Katz, None

A. Mcgeer, None

S. Smith, None

K. Weiss, None

A. E. Simor, None

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