Session: Poster Session: E. coli and Klebsiella sp. Enzymatic Resistance
Saturday, October 25, 2008: 12:00 AM
Room: Hall C
Background: Plasmid-mediated AmpC β-lactamases have been increasing in prevalence and diversity worldwide. The purpose of this study was to investigate the AmpC-bearing plasmids isolated from E. coli in Canadian water sources (WS) and compare them to clinical isolates (CI) from intensive care units (ICUs). Methods: 94 and 26 E. coli isolates producing CMY-2 AmpC β-lactamases were investigated from Canadian recreational beach/private well water sources and ICUs, respectively. Plasmids harboring CMY-2 were extracted and transformed by electroporation into E. coli DH10B. CMY-2 plasmids were selected for on LB plates containing ampicillin and cefoxitin. Plasmids were characterized by RFLP patterns digested with BglII and a multiplex PCR for replicon typing. Results: Replicon typing revealed that the CMY-2 plasmids were distributed among 4 predominant replicon types: repI1 (53.2%, 42.3%), repK/B (14.9%, 34.6%), repA/C (17%, 26.9%) and an unidentified (UI) replicon type (12.8%, 3.8%) from both WS and CI, respectively. Multiple replicon types were identified among 6.4% of water and 7.7% of clinical CMY-2 plasmids. RFLP patterns of plasmid transformant DNA from both WS and CI consisted of 4 clusters corresponding to the 4 prevalent replicon types. Genetically indistinguishable repK/B, repI1, and UI CMY-2 plasmids were identified among both water and CI. Conclusions: CMY-2 plasmids isolated from Canadian water and clinical E. coli isolates were divided into 4 clusters based on RFLP patterns corresponding to the prevalent replicon types: repI1, repK/B repA/C and UI. The presence of genetically indistinguishable CMY-2 plasmids in both Canadian water and clinical isolates demonstrates a possible link of the dissemination of these plasmids from contaminated water sources to humans.