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目的 研究质粒介导的喹诺酮耐药基因在医院内的流行情况,检测菌株的耐药性,分析菌株间的同源性. 方法 收集临床分离的耐喹诺酮产超光谱β-内酰胺酶(ESBLs)肠杆菌科细菌,利用PCR方法对质粒耐药基因进行检测,阳性菌株进行接合试验,然后检测药物对供体菌、受体菌和接合子最小抑菌浓度(MIC)值的变化,通过脉冲场电泳检测菌株间的同源性. 结果 所有菌株均未检出耐药基因qnrA与qnrC,其他7种耐药基因如qnrB均阳性,且部分菌株携带多个耐药基因.阳性菌株接合子对喹诺酮的耐药性增强并且有些质粒携带多种耐药基因,脉冲场电泳分析大肠埃希菌喹诺酮耐药株主要以发散为主,肺炎克雷伯菌主要以相对暴发流行为主. 结论 携带β-内酰胺酶基因的菌株,质粒介导的喹诺酮耐药基因检出率高,二者呈一定程度的共存.携带喹诺酮耐药基因的质粒水平转移,细菌对喹诺酮的耐药性增强,在免疫力低下人群,耐药菌株的传播更为迅速.“,”Objectives To determine the prevalence of plasmid-mediated quinolone resistance genes of Enterobacteriaceae in a local hospital,to test the strains for drug resistance,and to analyze the homology of the strains.Methods Clinical isolates producing ESBLs were collected,resistance genes in the plasmid were detected with PCR,and plasmid conjugation experiments were performed with Enterobacteriaceae carrying the PMQR gene.The E-test detections was used to determine the MIC of the donor,recipient,and transconjugants,and the homology of Enterobacteriaceae carrying the PMQR gene was analyzed with pulsed field electrophoresis.Results Almost all of the quinolone resistance genes except for qnrA and qnrC were detected in the tested strains.Ninety-six percent of strains carried a quinolone resistance gene,and 70％ of strains carried more than one quinolone resistance gene.Transconjugants had increased resistance to quinolones after conjugation,and some plasmids carried a multi drug resistance gene.The development of plasmid-mediated quinolone resistance in K.pneumoniae is more concentrated than that in E.coli.Conclusion The PMQR gene was often detected in ESBL-producing strains.The horizontal transfer of a plasmid carrying a quinolone resistance gene caused the clinical resistance of Enterobacteriaceae to quinolone to increase significantly.Moreover,drug-resistant bacteria spread rapidly in immunocompromised patients.