Title: Characterization of Multidrug-Resistant Escherichia coli by Plasmid Replicon Typing and Pulsed-Field Gel Electrophoresis Authors
Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 2, 2010
Publication Date: May 23, 2010
Citation: Thitaram, S.N., Lindsey, R.L., Meinersmann, R.J., Cray, P.J., Englen, M.D. 2010. Characterization of Multidrug-Resistant Escherichia coli by Plasmid Replicon Typing and Pulsed-Field Gel Electrophoresis. American Society for Microbiology Meeting. May 23-27, 2010. San Diego, CA. Poster A-1025. Technical Abstract: Background: Characterization of plasmids has particular clinical significance because genes encoding important traits such as antimicrobial resistance are frequently present in plasmids. Plasmid replicon typing is a multiplex PCR based method that can be used to classify 18 of the 26 known plasmid types in Enterobacteriaceae. The objective of this study was to analyze plasmid replicon types, antimicrobial phenotypes, and genetic relationships of 35 multidrug-resistant (MDR) Escherichia coli. Methods: A total of 35 E. coli isolates were selected based on antimicrobial phenotypes of clinically important drugs from 7 different food and companion animals. Pulsed-field gel electrophoresis (PFGE) was used to determine possible genetic relationships among E. coli isolates. Multiplex PCR was used to examine the incompatibility (Inc) replicon types. Linkage analysis was conducted with isolate antimicrobial resistances, replicon types, and animal sources. Results: A high degree of genotypic diversity was observed, with 34 distinct PFGE clusters found among the 35 isolates examined. A total of 15 different plasmid replicon types were detected and all isolates carried multiple replicon types. Overall Inc B/O plasmids were the most common type identified followed by Inc FIB. Significant linkage of Inc B/O was seen with sulfamethoxazole and ceftriaxone while Inc FIB was significantly linked with amoxicillin-clavulanic acid, ampicillin, chloramphenicol, and tetracycline. As expected, significant linkage of E. coli isolates was seen with amoxicillin-clavulanic acid, ampicillin, cefoxitin, tetracycline, and ceftiofur since they were used in isolate selection. The animal source of the isolate did not appear to have a correlation to cluster analysis based on PFGE. Conclusion: Inc B/O and FIB were the predominant replicon types among MDR E. coli isolates in this study. Additional research is warranted to determine the diversity and linkages associations with plasmids carrying antimicrobial resistance genes in E. coli.