质粒介导的克雷伯菌耐喹诺酮类药物机制研究

Mechanism of plasmid-mediated quinolone resistance of Klebsiella

目的了解华南地区qnr基因介导的克雷伯菌耐喹诺酮类药物的情况并研究其耐药机制。方法收集临床分离的克雷伯菌株共200株,其中产酸克雷伯菌6株。PCR方法筛查基因,琼脂稀释法测MIC,质粒结合试验,聚合酶链反应(PCR)通用引物扩增各组基因及测序。结果200株细菌中筛查到带qnr基因的菌株共2株(其中产酸克雷伯菌1株),均对环丙沙星敏感。进一步确证实验中证实2菌株都含qnr基因。2菌株经结合实验后在选择平板上都有菌生长,而且对环丙沙星的MIC值均有30倍以上的的提高。2株菌均有gyrASer83→Tyr突变,产酸克雷伯菌株有parCSer80→Ile突变。2株菌质粒PCR扩增的qnr产物测序结果与NCBI中qnr基因比对吻合率达100%。结论华南地区已有质粒介导的耐喹诺酮类菌株存在,它们能够跨种属转移,值得临床医生重视。

Objective To investigate the existence of plasmid-mediated quinolone resistance of Klebsiella in Southern China. Methods A total of 200 clinical isolates of Klebsiella spp. were collected from different cities in Southern China. The qnr genes were identified by PCR. Antimicrobial susceptibility test was performed by using agar dilution test. Plasmid conjugation, plasmid extraction and universal PCR for gene amplication of corresponding group was done, and the PCR products were sequenced subsequently. Results The qnr genes were identified in one Klebsiella pneumonae and one Klebsiella oxytoca. The plasmid conjugation tests were carried out in the both strains and then a MIC rise by about 30 folds was observed. The genes of mutation target enzymes （GyrA GyrB ParC ParE） were compared to the literatures, and the qnr gene sequence matched that of NCBI GenBank with 100%. Conclusions The plasmid-mediated quinolone resistances had been existing in KlebsieUa spp. in Southern China. The qnr can be tranfered in different bacteria, which should be highly concerned in clinics.