Prevalence of Plasmid-Mediated Quinolone Resistance Determinants over a 9-Year Period
Prevalence of Plasmid-Mediated Quinolone Resistance Determinants over a 9-Year Period
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DOI：
10.1128/aac.01051-08
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发表时间：
2009-02-01
影响因子：
4.9
通讯作者：
Hooper, David C.
中科院分区：
文献类型：
--
作者：
Kim, Hong Bin;Park, Chi Hye;Hooper, David C.
最近，发现了几种质粒介导的喹诺酮耐药（PMQR）基因，这些基因赋予低水平的喹诺酮耐药。为了评估韩国三级医院PMQR基因在十年内患病率的时间变化，我们从1998年至2001年和2005年至2006年的血液分离株中选择了每五株大肠埃希菌和肺炎克雷伯菌以及每三株阴沟肠杆菌。采用多重PCR方法筛选出6个PMQR基因[qnrA、qnrB、qnrC、qnrS、aac（6 '）-Ib-cr和qepA]，并通过直接测序进行验证，aac（6'）-Ib阳性PCR产物经BtsCI酶切鉴定aac（6 '）-Ib-cr变异体。在461株分离株中，37株（8%）具有6个PMQR基因中的一个;大肠杆菌13株（10%）; pneumoniae菌株; Clobacillus strains qnrB是最常见的PMQR基因，早在1998年就被发现，而qnrS、aac（6 '）-Ib-cr和qepA则是在2000年之后才出现的。所有分离株均不携带qnrA或qnrC。环丙沙星耐药率随时间的推移而增加（P < 0.001），PMQR基因的总体患病率有增加的趋势（P = 0.20）。PMQR阳性菌株对环丙沙星的耐药率和多重耐药率明显高于阴性菌株（P = 0.005和P < 0.001）。肠杆菌科中环丙沙星耐药频率的增加与PMQR基因患病率的增加有关，这种变化涉及PMQR基因多样性的增加，以及gyrA、parC或两者突变患病率的增加。PMQR阳性菌株，但不是PMQR阴性菌株。
Recently, several plasmid-mediated quinolone resistance (PMQR) genes conferring low levels of quinolone resistance have been discovered. To evaluate the temporal change in the prevalence of PMQR genes over a decade in a tertiary hospital in the Republic of Korea, we selected every fifth isolate of Escherichia coli and Klebsiella pneumoniae and every third isolate of Enterobacter cloacae between 1998 and 2001 and between 2005 and 2006 from a collection of blood isolates. Six PMQR genes [qnrA, qnrB, qnrC, qnrS, aac(6')-Ib-cr, and qepA] were screened by multiplex PCR and then confirmed by direct sequencing, and the aac(6')-Ib-positive PCR products were digested with BtsCI to identify the aac(6')-Ib-cr variant. Of 461 isolates, 37 (8%) had one of the six PMQR genes; 13 (5%) of 261 E. coli strains, 13 (10%) of 135 K. pneumoniae strains, and 11 (17%) of 65 E. cloacae strains. qnrB was the most common PMQR gene and was found as early as 1998, whereas qnrS, aac(6')-Ib-cr, and qepA emerged after 2000. None of the isolates carried qnrA or qnrC. Ciprofloxacin resistance increased over time (P < 0.001), and the overall prevalence of PMQR genes tended to increase (P = 0.20). PMQR-positive isolates had significantly higher ciprofloxacin resistance and multidrug resistance rates (P = 0.005 and P < 0.001, respectively). The increasing frequency of ciprofloxacin resistance in Enterobacteriaceae was associated with an increasing prevalence of PMQR genes, and this change involved an increase in the diversity of the PMQR genes and also an increase in the prevalence of the mutations in gyrA, parC, or both in PMQR-positive strains but not PMQR-negative strains.