Send to

Choose Destination
Diagn Microbiol Infect Dis. 2009 Mar;63(3):319-26. doi: 10.1016/j.diagmicrobio.2008.12.001.

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.

Author information

Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.


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.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center