Surveillance for plasmid-mediated quinolone resistance determinants in Enterobacteriaceae within the Calgary Health Region, Canada: the emergence of aac(6')-Ib-cr.
OBJECTIVE
A study was designed to determine the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants among clinical isolates of Enterobacteriaceae from the Calgary Health Region (CHR).


METHODS
During January and February 2004 and January and February 2007, 564 non-repeat isolates of Escherichia coli, Klebsiella spp., Proteus mirabilis and Morganella morganii resistant to ciprofloxacin and/or tobramycin were screened for PMQR determinants using a multiplex PCR for qnrA, qnrS and qnrB and aac(6')-Ib genes; aac(6')-Ib-cr was further identified by digestion with BstF5I.


RESULTS
In 2004, 6/139 (4%) of the resistant E. coli were positive for aac(6')-Ib-cr. In 2007, 53/398 (13%) were positive for aac(6')-Ib-cr, 3/398 (0.8%) were positive for qnrS, and one isolate was positive for both. All the isolates were present in urines and the majority [40/63 (63%)] were submitted from community collection sites; 8 (13%) isolates co-produced AmpC beta-lactamases and 34 (54%) co-produced CTX-M-15. aac(6')-Ib-cr was present in one Klebsiella pneumoniae and one P. mirabilis, whereas one isolate of K. pneumoniae was positive for both aac(6')-Ib-cr and qnrB.


CONCLUSIONS
Our results showed that isolates with aac(6')-Ib-cr, often associated with CTX-M-15, are emerging among fluoroquinolone-resistant E. coli in the CHR. Our study suggests that surveillance for PMQR determinants should be undertaken on a regular basis.
Pitout
Johann D D
JD
Division of Microbiology, Calgary Laboratory Services, University of Calgary, #9, 3535 Research Road NW, Calgary, Alberta, Canada T2L 2K8. johann.pitout@cls.ab.ca
Wei
Yi
Y
Church
Deirdre L
DL
Gregson
Daniel B
DB
D000416:Alberta / Q000453:epidemiology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D006801:Humans; D010957:Plasmids / Q000235:genetics*; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D015363:Quinolones