Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6118388 | International Journal of Antimicrobial Agents | 2011 | 4 Pages |
Abstract
To characterise the prevalence of β-lactamases and 16S rRNA methylase genes amongst clinical Klebsiella pneumoniae isolates carrying plasmid-mediated quinolone resistance (PMQR) determinants in China, 59 non-duplicate K. pneumoniae isolates harbouring at least one PMQR gene were screened for common β-lactamases and 16S rRNA methylases genes. The genetic relatedness of the isolates was analysed by pulsed-field gel electrophoresis (PFGE). Most of PMQR gene-positive isolates carried no substitutions within the quinolone resistance-determining regions (QRDRs) or single point mutation in GyrA or ParC. Over one-half (52.5%) of the isolates exhibited decreased susceptibility to ciprofloxacin [minimum inhibitory concentration (MIC) = 0.5-2 μg/mL] or low-level resistance to ciprofloxacin (MIC = 4-8 μg/mL). qnr, aac(6â²)-Ib-cr and qepA were positive in 52 (88.1%), 16 (27.1%) and 3 (5.1%) isolates, respectively. The identified genes for β-lactamases were distributed as follows: blaTEM, 50.8%; blaSHV, 91.5%; blaCTX-M, 55.9%; blaDHA, 59.3%; and blaOXA-1, 22.1%. armA and rmtB were detected in 16.9% and 3.4% of isolates, respectively. All qnrB were detected in DHA-producing K. pneumoniae. Approximately 81.3%, 68.8% and 43.8% of aac(6â²)-Ib-cr carrying isolates produced OXA-1, DHA and ArmA, respectively. In conclusion, owing to few QRDR substitutions, most of the PMQR gene-carrying K. pneumoniae isolates exhibited low-level resistance to fluoroquinolones. qnr appears to be the predominant PMQR gene and it presented a significant correlation with blaSHV, blaCTX-M and blaDHA, whereas aac(6â²)-Ib-cr exhibited a close relationship with blaOXA-1, blaDHA and armA. qepA was rarely detected in this study.
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Authors
Yanping Luo, Jiyong Yang, Youjiang Zhang, Liyan Ye, Leili Wang, Ling Guo,