CJIDMM Canadian Journal of Infectious Diseases and Medical Microbiology 1712-9532 Pulsus Group Inc 848194 10.1155/2007/848194 Original Article ESBL Genotypes in Fluoroquinolone-Resistant and Fluoroquinolone-Susceptible ESBL-Producing Escherichia coli Urinary Isolates in Manitoba Lagacé-Wiens Philippe RS plagacewiens@hotmail.com 1 2 Nichol Kim A 2 Nicolle Lindsay E 1 3 DeCorby Mel R 1 2 McCracken Melissa 1 4 Alfa Michelle J 1 Mulvey Michael R 4 Zhanel George G 1 2 1 Department of Medical Microbiology and Infectious Diseases Faculty of Medicine University of Manitoba Canada umanitoba.ca 2 Clinical Microbiology Health Sciences Centre Canada hsc.mb.ca 3 Department of Internal Medicine and Health Sciences Centre Faculty of Medicine University of Manitoba Canada umanitoba.ca 4 Nosocomial Infections National Microbiology Laboratory Public Health Agency of Canada Winnipeg Manitoba Canada phac-aspc.gc.ca 2007 18 2 133 137 16 2 2006 2 9 2006 2007 Copyright © 2007 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

OBJECTIVE: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are increasingly common in nosocomial and community settings. Furthermore, fluoroquinolone (FQ) and even multidrug resistance (MDR) appear to be associated with certain ESBL genotypes. The purpose of the present study was to determine which ESBL genotypes are associated with FQ and MDR in E coli urinary isolates in Manitoba.

METHODS: The authors determined the antimicrobial susceptibility, genetic similarity and ESBL genotype of 27 FQ-resistant and seven FQ-susceptible, ESBL-producing urinary isolates submitted to the clinical microbiology laboratories of two teaching hospitals between October 2000 and April 2005. Susceptibilities to beta-lactams, FQs, trimethoprim-sulfamethoxazole (SXT), doxycycline (DOX), gentamicin (GM) and tigecycline were determined by microbroth dilution; pulsed-field gel electrophoresis (PFGE) was used to determine genetic relatedness, and ESBL genotype was determined by polymerase chain reaction and sequencing.

RESULTS: Of 34 ESBL-producing organisms, 27 (79.4%) were found to be ciprofloxacin (CIP) resistant, 27 (79.4%) were SXT resistant, eight (23.5%) were GM resistant and 29 (85.3%) were DOX resistant. Twenty-three (67.6%) had MDR, with concomitant resistance to CIP and SXT; 16 had concomitant resistance to CIP, SXT and DOX; and seven (20.6%) had MDR, with concomitant resistance to CIP, SXT, DOX and GM. All isolates were susceptible to tigecycline. Of 27 FQ-resistant ESBL-producing organisms, seven (25.9%) were genotype CTX-M-14, 19 (70.4%) were genotype CTX-M-15 and one (3.7%) was genotype CTX-M-24. Among the seven FQ-susceptible strains, three (42.8%) expressed SHV-type enzymes, three (42.8%) expressed TEM-type enzymes and one (14.3%) expressed CTX-M-9. CTX-M-15 was the most common MDR-associated genotype. Of a total of 19 strains, 18 (94.7%) were resistant to FQs and SXT; 15 (78.9%) were resistant to FQs, SXT and DOX; and five (26.3%) were resistant to FQs, SXT, DOX and GM. PFGE analysis revealed genetic similarity within CTX-M-15-producing isolates only.

CONCLUSION: CTX-M-15 in E coli is strongly associated with an MDR phenotype compared with other genotypes. CTX-M-14 is associated with FQ resistance only. PFGE suggests clonality of CTX-M-15-producing isolates within and among hospitals.

CTX-M-15 ESBL Escherichia coli Fluoroquinolone-resistant Molecular epidemiology Multidrug-resistant