JAC Advance Access originally published online on July 3, 2009
Journal of Antimicrobial Chemotherapy 2009 64(3):552-555; doi:10.1093/jac/dkp225
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Original research |
Identification of multidrug- and carbapenem-resistant Acinetobacter baumannii in Canada: results from CANWARD 2007
1 National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada 2 Department of Medical Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada 3 Department of Laboratory Medicine and Pathology, University of Alberta Hospital, Edmonton, Alberta, Canada 4 Department of Microbiology and Medicine, McGill University Health Centre, Montreal, Quebec, Canada 5 Department of Clinical Microbiology, Health Sciences Centre, Winnipeg, Manitoba, Canada
Received 23 March 2009; returned 6 May 2009; revised 26 May 2009; accepted 4 June 2009
* Corresponding author. Antimicrobial Resistance and Nosocomial Infections, National Microbiology Laboratory, 1015 Arlington St., Winnipeg, Manitoba, Canada, R3E 3R2. Tel: +1-204-789-2133; Fax: +1-204-789-5020; E-mail: Michael_mulvey{at}phac-aspc.gc.ca
Objectives: Multidrug-resistant (MDR) Acinetobacter baumannii is a growing concern in many countries. This report describes patient demographics, antimicrobial susceptibilities and molecular characteristics of A. baumannii cases identified through the Canadian Ward Surveillance Study (CANWARD). In addition, clinical cases involving MDR carbapenem-resistant A. baumannii are also detailed in this report.
Methods: From January to December 2007, 12 hospital centres across Canada submitted pathogens from clinics, emergency rooms, intensive care units and medical/surgical wards as part of the CANWARD study. MICs were determined using microbroth dilution (CLSI). PCR and sequence analysis identified OXA genes among carbapenem-resistant isolates. PFGE was used to determine genetic relatedness and compare representatives of the Midlands 2 strain, OXA-23 clone 1 or 2, T strains and isolates collected from military sources.
Results: This study identified A. baumannii in 0.33% (n = 26) of infections. The majority of isolates remained susceptible to the antimicrobials tested, however, 7.7% (n = 2) displayed an MDR phenotype, including resistance to carbapenems. In one isolate blaOXA-58 was found to be the likely cause of carbapenem resistance while the other isolate had an insertion sequence element upstream of its intrinsic blaOXA-51. The clinical data of these two isolates suggest that one is travel-related while the source of the other remains unknown.
Conclusions: A. baumannii infections from Canadian hospitals were relatively low. Carbapenem-resistant MDR A. baumannii were also rare and unrelated to previously observed isolates from military sources. Continued surveillance in Canada is suggested in order to determine if such organisms will become a problem.
Keywords: OXA-type β-lactamases , surveillance , MICs