尿路感染产NDM-5大肠埃希菌对碳青霉烯类抗菌药物耐药机制研究

Study on the carbapenem resistance mechanism of NDM-5 Escherichia coli in urinary tract infection

目的探讨尿路感染大肠埃希菌对碳青霉烯类抗菌药物耐药机制及流行特点,为其治疗提供实验依据。方法收集浙江省人民医院2018年6月-2020年6月门诊及住院患者尿路感染大肠埃希菌1574株,应用法国梅里埃VITEK 2 Compact检测大肠埃希菌药物敏性;通过WHONET 5.6软件统计药敏结果;应用PCR法检测相关碳青霉烯酶耐药基因(bla_(KPC)、bla_(NDM)、bla_(VIM)和bla_(IMP));应用多克隆序列位点测定(MLST)方法检测菌株克隆型别;通过接合转移试验验证耐药基因转移。结果共分离尿路感染大肠埃希菌1574株,CRE菌株分离率为1.65%,PCR鉴定出7株携带、bla_(NDM-5)基因菌株,MLST数据显示这些菌株属于不同克隆型别。此外,7株携带bla_(NDM-5)基因菌株可以成功地将其对碳青霉烯类耐药的表型转移到受体菌大肠埃希菌C600菌株中。结论本院尿路感染大肠埃希菌对碳青霉烯类抗菌药物的耐药机制主要是产NDM-5型碳青霉烯酶。bla(NDM-5)耐药基因主要定位于质粒进行水平播散,应引起临床高度重视,迫切需要密切监测携带bla(NDM-5)基因的菌株的进一步传播。

Objective To investigate the carbapenem resistance mechanism and epidemic characteristics in Escherichia coli from urinary tract infection,and to provide experimental basis for its treatment.Methods E.coli strains isolated from outpatients and inpatients with urinary tract infection in Zhejiang Provincial People's Hospital from June 2018 to June 2020 were collected,and the drug sensitivity of E.coli was detected by VITEK 2 Compact system.The results of drug sensitivity were analyzed by WHONET 5.6 software.The carbapenemase resistance genes(bla_(KPC)、bla_(NDM)、bla_(VIM) and bla_(IMP))were detected by PCR,and the clonal types were detected by MLST.Resistant gene transfer was verified by conjugation transfer test.Results A total of 1574 E.coli strains were isolated from patients with urinary tract infection.The isolation rate of CRE was 1.65%.Seven strains carrying bla(NDM-5) gene were identified by PCR and sequencing.MLST showed that these strains belonged to different clone types.In addition,seven strains carrying 6ZaNDM_5 gene could successfully transfer their carbapenem resistant phenotype to E.coli EC600 strain.Conclusion The resistance mechanism of carbapenems resistance E.coli is mainly producing carbapene-mase,especially producing NDM-5 enzyme.The bla(NDM-5) gene is mainly located in the plasmids for horizontal dissemination,which should be attached great importance to in clinics.It is urgent to closely monitor the further spread of bla(NDM-5) gene carrying strains.