Prevalence of plasmid-mediated quinolone resistance qnr genes in Central China

A total of 179 Gram-negative bacteria strains collected in Wuhan from 2005 to 2006 were screened for qnrA, qnrB and qnrS genes by polymerase chain reaction (PCR). The qnrAgenes were detected in 3.88% of Escherichia coli and 7.69% of Enterobacter cloacae, whereas the qnrB genes were found in 6.20% of E. coli and 7.69% of E. cloacae. 2.33% ofE. coli and 18.92% of Klebsiella pneumoniae were positive for the qnr gene in PCR. Minimal inhibitory concentrations (MICs) results of ciprofloxacin confirmed that qnrS gene could be present in isolates susceptible to quinolones. Furthermore, the results indicated that qnr genes were identified on transferable plasmids, and quinolone resistance can be transferred by bacterial conjugation.   Key words: qnr, gram-negative pathogens, plasmid-mediated.