碳青霉烯类耐药肠杆菌科细菌分子流行病学分析

目的研究西部战区总医院碳青霉烯类耐药肠杆菌科细菌(CRE)的流行病学特征及耐药机制。方法收集2015年1月-2018年12月临床各种标本分离出的CRE 121株,采用VITEK 2-Compact全自动微生物分析仪进行鉴定和体外药敏试验,聚合酶链反应(PCR)法及测序检测碳青霉烯酶、ESBL酶、AmpC酶和膜孔蛋白基因;肠杆菌科基因间重复一致序列PCR(ERIC-PCR)进行同源性分析。结果121株CRE中碳青霉烯酶阳性96株,其中65株产blaKPC、25株产blaNDM-1、7株产blaOXA-48、2株产blaVIM,有2株同时产blaKPC和blaNDM-1,1株同时产blaKPC和blaVIM;未检测到blaIMP、blaGES基因;blaSHV、blaTEM和blaDHA检出率分别为46.3%、47.1%和37.2%;OMPF、OMPC缺失/突变率分别为48.1%、84.6%,OMPK35、OMPK36缺失/突变率分别为35.7%、91.1%。药敏结果分析发现121株CRE对青霉素、头孢菌素类抗生素耐药率高,对阿米卡星耐药率最低。ERIC-PCR结果显示56株碳青霉烯类耐药克雷伯菌有5种基因型;26株碳青霉烯类耐药大肠埃希菌有3种基因型;23株碳青霉烯类耐药阴沟肠杆菌有3种基因型。结论该院临床分离的CRE以blaKPC为主要耐药基因,其次为blaNDM-1;部分CRE既携带碳青霉烯酶基因,同时合并膜孔蛋白基因缺失/突变。从分型结果得出,部分菌株同源性非常高,存在克隆传播现象。

Molecular epidemiological analysis of carbapenem-resistant Enterobacteriaceae strains

Objective To investigate the epidemiological characteristics and resistance mechanism of carbapenem-resistant Enterobacteriaceae(CRE),which were isolated in the General Hospital of Western Theater Command from January 2015 to December 2018.Methods A total of 121 CRE strains were isolated from patients.The in vitro antimicrobial susceptibility was determined by VITEK 2-Compact automatic microbiological analysis system.PCR method was used to detect the genes encoding carbapenemases,ESBLs,AmpC,and outer membrane porin genes.Enterobacterial repetitive intergenic consensus polymerase chain action(ERIC-PCR)was used to analyze homology of bacterial isolates.Results A total of 96 strains were carbapenemase producing Enterobacteriaceae(CPE),including blaKPC(65,67.7%),blaNDM-1(25,26.0%),blaOXA-48(7,7.3%),and blaVIM(2,2.1%).Two strains carried blaKPC and blaNDM-1 genes.One strain carried blaKPC and blaVIM simultaneously.The blaIMP and blaGES genes were not identified.The prevalence of blaSHV,blaTEM and blaDHA gene was 46.3%,47.1%,and 37.2%,respectively.The deletion or mutation rates of OMPF and OMPC were 48.1%and 84.6%.Deletion or mutation of OMPK35 and OMPK36 was identified in 35.7%and 91.1%of the strains,respectively.These strains were highly resistant to penicillins and cephalosporins,but least resistant to amikacin.ERIC-PCR results showed that 56 carbapenem-resistant K.pneumoniae strains were classified into 5 different genotypes,26 E.coli and 23 E.cloacae strains could be classified into 3 genotypes,respectively.Conclusions The main encoding gene of CRE strains is blaKPC in this hospital,followed by blaNDM-1.Some isolates carried both carbapenemase gene and deleted/mutated gene of outer membrane porin.Some strains show high homology,suggesting clonal transmission in the hospital.