Coexistence of qnrB4 and qnrS1 in a clinical strain of Klebsiella pneumoniae
Coexistence of qnrB4 and qnrS1 in a clinical strain of Klebsiella pneumoniae
复制标题
qnrB4 和 qnrS1 在肺炎克雷伯菌临床菌株中的共存
DOI：
10.1111/j.1745-7254.2008.00757.x
复制
发表时间：
2008-03-01
影响因子：
8.2
通讯作者：
Wang, Ming-gui
中科院分区：
文献类型：
--
作者：
Hu, Fu-pin;Xu, Xiao-gang;Wang, Ming-gui
摘要：目的确定一株临床肺炎克雷伯菌（K pneumoniae）携带的2个质粒介导的喹诺酮类耐药基因qnrB4和qnrS1的定位及其相互关系，并分析其遗传背景。方法：采用Southern印迹法对携带qnrB4或qnrS1的质粒进行鉴定。将含有qnrB4或qnrS1的HindIII片段克隆到puc18质粒中并测序。结果：qnrB4和qnrS1分别位于pHS7和pHS8两个质粒上，大小分别为180 kb和45 kb。通过偶联得到一个携带qnrB4的质粒pHS7和另一个携带qnrB4和qnrS1的质粒pHS9。携带qnrS1的质粒pHS8也通过转化转移到J53上。J53转缀合物、仅携带qnrB4、仅携带qnrS1和同时携带qnrB4和qnrS1的转化物的环丙沙星最低抑制浓度（MIC）分别为0.19、0.25和0.25 mg/L，而肺炎K临床亲本菌株的MIC为0.75 mg/L。qnrB4位于sul1型整合子中，其上游序列为blaDHA-1、ampR和psp基因，插入序列为IS26，下游序列为sap基因。qnrS1不位于整合子中，但IS26在qnrS1的上下游均有发现，IS2在qnrS1的正上游均有发现。结论：qnrB和qnrS可被一株临床肺炎克雷伯菌同时携带。这两个基因由两个不同的质粒携带，在质粒DNA结构上具有不同的遗传环境。
AbstractAim:To identify the location and the relationship, and to analyze the genetic background of 2 plasmid-mediated quinolone resistance genes, qnrB4 and qnrS1, carried by a clinical strain of Klebsiella pneumoniae (K pneumoniae).Methods:The plasmids carrying qnrB4 or qnrS1 were identified by Southern blotting. A HindIII fragment containing qnrB4 or qnrS1 was cloned into plasmid puc18 and sequenced.Results:qnrB4 and qnrS1 were located on 2 different plasmids, pHS7 and pHS8, and were 180 and 45 kb in size, respectively. A transconjugant carrying plasmid pHS7 bearing qnrB4 and another transconjugant carrying pHS9 bearing qnrB4 and qnrS1 were obtained by conjugation. Plasmid pHS8 bearing qnrS1 was also transferred to J53 by transformation. The ciprofoxacin minimal inhibitory concentrations (MIC) for J53 transconjugants or the transformant carrying qnrB4 only, qnrS1 only, and both qnrB4 and qnrS1 were 0.19, 0.25, and 0.25 mg/L, respectively, while the parent clinical strain of K pneumoniae had a MIC of 0.75 mg/L. qnrB4 was located in a sul1-type integron with blaDHA-1, ampR and psp genes in upstream and insertion sequence IS26, and sap genes in downstream of qnrB4. qnrS1 was not located in an integron, but IS26 was found both upstream and downstream, and IS2 was found directly upstream of qnrS1.Conclusion:qnrB and qnrS can be harbored simultaneously by a single clinical strain of K pneumoniae. These 2 genes are carried by 2 different plasmids and have different genetic environments in plasmid DNA structure.