title: Characterization of a cmeABC operon in a quinolone-resistant Campylobacter coli isolate of Irish origin.
abstract: In this study, a tripartite-operon-encoding efflux system together with its regulatory gene was characterized in an Irish Campylobacter coli isolate CIT-382 showing high-level resistance to nalidixic acid and ciprofloxacin. Sequence comparisons revealed significant homology between C. coli and the cmeABC operon of Campylobacter jejuni. Conservation of functional sequence domains and motifs were noted among C. coli and similar operons in unrelated organisms. A transcriptional regulatory gene cmeR located proximal to cmeABC was also identified. C. coli CIT-382 harbored the Thr-86-Ile amino acid substitution in the gyrA gene. Accumulation studies with ethidium bromide in the presence of known efflux pump inhibitors confirmed the presence of efflux pump activity in C. coli CIT-382. The efflux pump inhibitor PAbetaN had no effect on the MICs to quinolones. Our data suggest that the gyrA gene mutation is the main contributor to the high-level nalidixic acid and ciprofloxacin resistance observed in this Irish C. coli CIT-382 isolate.
authors.affiliation: Molecular Diagnostics Unit, Cork Institute of Technology, Bishopstown, Cork, Ireland., Centre for Food Safety, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Deborah
authors.initials: D
authors.lastname: Corcoran
authors.forename: Teresa
authors.initials: T
authors.lastname: Quinn
authors.forename: Leslie
authors.initials: L
authors.lastname: Cotter
authors.forename: Fiona
authors.initials: F
authors.lastname: O'Halloran
authors.forename: Séamus
authors.initials: S
authors.lastname: Fanning
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017000:Campylobacter coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D016123:Campylobacter jejuni / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D002939:Ciprofloxacin / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D007494:Ireland; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D009268:Nalidixic Acid / Q000494:pharmacology; D009876:Operon; D015363:Quinolones / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D004269:DNA, Bacterial; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009268:Nalidixic Acid; D015363:Quinolones