title: Mechanisms of resistance and mobility among multidrug-resistant CTX-M-producing Escherichia coli from Canadian intensive care units: the 1st report of QepA in North America.
abstract: We studied the molecular mechanisms of resistance and mobility of 18 multidrug-resistant CTX-M-producing Escherichia coli isolates isolated from patients in Canadian intensive care units. Fluoroquinolone-resistant isolates (83.3%) had mutations in gyrA and parC. Plasmid-mediated quinolone resistance genes qnr (A, B, and S), qepA, and aac(6')-Ib-cr were detected in 0%, 5.6%, and 44.4%, respectively. Sulfamethoxazole/trimethoprim-resistant isolates (61.1%) carried a dfr gene, and 10 (90.9%) of the 11 carried 1 or more sul genes. Gentamicin-resistant isolates (27.8%) carried the aac(3')-II gene, and doxycycline-resistant isolates (33.3%) carried 1 or more tet efflux genes. Both genetically related and unrelated groups of E. coli harboring extended-spectrum beta-lactamases were observed. The bla(CTX-M) genes were primarily located on diverse IncF plasmids of multiple replicon types downstream of the ISEcp1 element. The spread of the bla(CTX-M) genes among E. coli in Canada occurs through a diversity of different mechanisms and does not correspond to a single CTX-M determinant, or a single clone, or a single plasmid but rather through the combination of clonal spread of virulent strains and acquisition of diverse CTX-M-bearing plasmids. We report the 1st qepA-producing E. coli in North America.
authors.affiliation: Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada. trishbaudry@hotmail.com
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Baudry
authors.forename: Kim
authors.initials: K
authors.lastname: Nichol
authors.forename: Melanie
authors.initials: M
authors.lastname: DeCorby
authors.forename: Philippe
authors.initials: P
authors.lastname: Lagacé-Wiens
authors.forename: Erin
authors.initials: E
authors.lastname: Olivier
authors.forename: Dave
authors.initials: D
authors.lastname: Boyd
authors.forename: Michael R
authors.initials: MR
authors.lastname: Mulvey
authors.forename: Daryl J
authors.initials: DJ
authors.lastname: Hoban
authors.forename: George G
authors.initials: GG
authors.lastname: Zhanel
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D002170:Canada; D016000:Cluster Analysis; D003428:Cross Infection / Q000382:microbiology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D005838:Genotype; D006801:Humans; D007362:Intensive Care Units; D010957:Plasmids; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C524438:QepA protein, E coli; D001618:beta-Lactamases