耐碳青霉烯鲍曼不动杆菌耐药机制及分子流行病学研究

Molecular epidemiology and multidrug resistance mechanisms of carbapenem-resistance Acinetobacter baumannii

目的:阐明耐碳青霉烯鲍曼不动杆菌(CRAB)主要耐药机制和分子流行病学特征。方法:PCR方法检测常见碳青霉烯酶基因,PCR-RELP分型及基因测序检测整合子Ⅰ和ISCR1,ERIC-PCR及聚类分析研究克隆相关性。结果:碳青霉烯酶基因NDM、IMP、VIM、OXA-23-like、OXA-24-like、OXA-51-like、OXA-58-like检出率分别为4.1%、22.9%、26.0%、67.7%、63.5%、46.8%、65.6%。整合子Ⅰ可变区分为12个耐药基因盒排列类型,A6和A12首次在鲍曼不动杆菌中发现;ISCR1可变区分为6个类型。将耐药机制、ERIC-PCR及聚类分析结合临床资料综合分析,CRAB感染患者均为散发,粪便中CRAB不是临床感染来源。结论:CRAB主要耐药机制是产碳青霉烯酶及整合子Ⅰ、ISCR1携带率高,ERIC-PCR基因分型结合耐药机制研究适用于分子流行病学调查。

Objective To clarify the molecular epidemiology and multidrug resistance mechanisms of carbapenem-resistance Acinetobacter baumannii（CRAB）. Methods Carbapenemase genes were analyzed by PCR. Class I integron and ISCRI were analyzed by PCR- RFLP, and cloning correlation was performed by ERIC- PCR and cluster analysis. Results The carriage rate of carbapenemase gene blaNDM,blalMP, blaVIM,blaOXA- 23-1ike,blaOXA-24-1ike, blaOXA-51-1ike,and blaOXA-58-1ike were 4.1% ,22.9% ,26.0% ,67.7% ,63.5% , 46.8%,and 65.6%,respectively. Twelve different gene cassette arrays were found in variable region of class I integron-positive isolates. A6 and A12 were first described in Acinetobacter baumannii,and 6 different gene cassette arrays were found in variable region of ISCR1 -positive isolates. Resistance mechanisms, ERIC-PCR and cluster analysis combined with clinical information, indicated that patients who were infected by CRAB were sporadic and inpatient stool specimens were not the source of clinical infection. Conclusions Mechanisms of carbapenem resistant Acinetobacter baumannii arc mainly producing carbapenemases and carrying class I integron and ISCR1. ERIC-PCR genotyping technologies combined with resistance mechanisms are applicable for molecular epidemiology studies.