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

作者：Baudry Patricia J^*; Nichol Kim; DeCorby Melanie; Lagace Wiens Philippe; Olivier Erin; Boyd Dave; Mulvey Michael R; Hoban Daryl J; Zhanel George G

来源：Diagnostic Microbiology and Infectious Disease, 2009, 63(3): 319-326.

DOI：10.1016/j.diagmicrobio.2008.12.001

• Escherichia coli
• Extended-spectrum beta-lactamase
• CTX-M
• Characterization
• Plasmid
• Multidrug-resistant
• QepA

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 go-A 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 I I carried I or more sul genes. Gentamicin-resistant isolates (27.8%) carried the aac(3')-II gene, and doxycycline-resistant isolates (33.3%) carried I 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.

• 出版日期2009-3