Prevalence of β-lactamases and 16S rRNA methylase genes amongst clinical Klebsiella pneumoniae isolates carrying plasmid-mediated quinolone resistance determinants

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• 作者：Yanping Luo^a ; Jiyong Yang ; ^a ; ^{yangjy301@hotmail.com} ; Youjiang Zhang^a ; Liyan Ye^a ; Leili Wang^a ; Ling Guo^a
• 关键词：Klebsiella pneumoniae ; Plasmid-mediated quinolone resistance ; &#x3b2 ; -Lactamase ; Methylase
• 刊名：International Journal of Antimicrobial Agents
• 出版年：2011
• 出版时间：April 2011
• 年：2011
• 卷：37
• 期：4
• 页码：352-355
• 全文大小：129 K

文摘

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(6′)-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: bla_TEM, 50.8 % ; bla_SHV, 91.5 % ; bla_CTX-M, 55.9 % ; bla_DHA, 59.3 % ; and bla_OXA-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(6′)-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 bla_SHV, bla_CTX-M and bla_DHA, whereas aac(6′)-Ib-cr exhibited a close relationship with bla_OXA-1, bla_DHA and armA. qepA was rarely detected in this study.