碳青霉烯类非敏感肠杆菌科细菌分子流行病学研究

Molecular epidemiological study of Enterobacteriaceae species with decreased susceptibility to carbapenems

目的调查碳青霉烯类抗生素非敏感肠杆菌科细菌的流行情况,并研究其耐药性传播方式。方法收集本院临床分离的碳青霉烯类抗生素非敏感肠杆菌科细菌34株,用Vitek2 Compact系统进行细菌鉴定和常规药敏检测,改良Hodge试验筛选产碳青霉烯酶菌株,用肠杆菌基因间重复一致序列(enterobacterial repetitive intergenic consensus,ERIC)-PCR进行分子流行病学调查。PCR扩增Int 1、Int 2、Int 3整合酶基因,质粒接合和消除试验研究细菌耐药基因的传播方式。结果 19株细菌改良Hodge试验阳性。来自7个不同科室的12株大肠埃希菌和17株阴沟肠杆菌可以分为3种和6种基因型,来自4个不同科室的5株肺炎克雷伯菌只有1种基因型。27株菌Int 1基因阳性,未检出Int 2和Int 3基因。除骨科1株阴沟肠杆菌外,其余33株细菌质粒消除和接合试验均成功。结论本院碳青霉烯类抗生素非敏感肠杆菌科细菌主要发生在外科各科室;所有肺炎克雷伯菌和泌尿外科大肠埃希菌属同一基因型,表明此类菌株呈局部流行;碳青霉烯类抗生素非敏感肠杆菌科细菌耐药性主要通过质粒传播。

Objective To investigate the molecular epidemiological status of Enterobacteriaceae species with decreased susceptibility to carbapenems and the transmission mode of drug-resistant strains in the species. Methods Thirty-four Enterobacteriaceae strains with decreased susceptibility to carbapenems were collected from outpatient service and wards in our hospital. The bacteria identification and the antibiotic sensitivity test were performed routinely by Vitek2 Compact system. The modified Hodge test （MHT） was used to screen the strains producing carbapenemases, and enterobacterial repetitive intergenic consensus （ERIC） -PCR was used to investigate the mo- lecular epidemiology. The transmission mode of drug-resistant species was analyzed by amplifying integrase genes Int 1, 2 and 3 with PCR and plasmid conjugation transfer test. Results Nineteen of the 34 isolates were positive in the detection of modified Hodge test. The results of ERIC-PCR indicated that 12 strains of E. coli and 17 strains of E. cloacae from 7 divisions in our hospital were divided in- to 3 and 6 genotypes, respectively. Only one genotype was exhibited in the 5 K. pneumonia isolates from 4 divisions. Of the total 34 strains, 33 were positive in the plasmid conjugation transfer test, and one （E. cloacae） negative strain was from the department of Or- thopaedics. Conclusions The Enterobacteriaceac species with decreased susceptibility to earbapenems were prevalent in the depart- ment of Surgery. E. coli isolates from the ward of Urology and all of the K. pneumonias belonged to identical genotype, indicating that the strain exhibited local prevalence. The transmission of drug resistance in Enterobacteriaceae species with decreased susceptibility to earbapenems was mediated by plasmid conjugation.