Molecular characterization of ciprofloxacin resistant and/or beta-lactamase producing Escherichia coli from the Vancouver Coastal Health region

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Gonsalves, Elizabeth A.
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Emergent multidrug resistant Escherichia coli increase clinical challenges. This thesis describes the resistance patterns, molecular epidemiology and mechanisms, for 315 E. coli from patients in the Vancouver Coastal Health Region for 2006/2007. Automated susceptibility testing was confirmed via E-test® for AmpC and/or ESBL production. PFGE, RFLP and PCR were used to assess genotypic relationships, and plasmid character. AmpC production was facilitated mainly by promoter mutations (54.5%). The principal ESBL detected was CTX-M-15 (49.5%). An unidentified ESBL-producer, with a pI near 8.3, was detected. A plasmid displayed variant resistance phenotypes dependent on selective growth media. A positive correlation between ST131 with CTX-M-15 and CIPR indicated the dissemination of companion phenotypes. Ciprofloxacin resistance resulted mainly (98.0%) from a double gyrA mutation. Overall fluoroquinolone resistance was not assessable due to exclusive selection parameters in this evaluation. Fluoroquinolone resistance factors require further examination to understand what causes resistant phenotypes exclusive of chromosomal mutations. ii
epidemiology, resistance, fluoroquinolone, ciprofloxacin, beta-lactamase, ESBL, E. coli, AmpC