耐碳青霉烯类鲍氏不动杆菌金属β-内酰胺酶检测与同源性分析

Detection of metallo-β-lactamases in carbapenem-resistant Acinetobacter baumannii and analysis of homology

目的分析医院耐碳青霉烯类鲍氏不动杆菌(CRAB)产金属β-内酰胺酶及菌株间同源性。方法收集医院2012年8-12月临床分离的耐碳青霉烯类鲍氏不动杆菌共51株,用VITEK-2药敏分析系统进行药敏试验,用EDTA纸片协同试验筛查金属酶表型,PCR检测IMP、SIM-1、VIM、NDM-1型金属酶基因;重复序列聚合酶链反应(REP-PCR)方法分析菌株同源性。结果 51株CRAB对多种抗菌药物耐药,EDTA纸片协同试验检测金属酶仅有1株阳性,阳性率1.96%,51株CRAB经PCR检测后仅有1株携带了NDM-1型基因,未检测出IMP、SIM-1、VIM型基因;用REP-PCR法可将51株CRAB分为4个基因型(A-F),其中A型48株,占94.12%,为主要流行株;B、C、D各有1株。结论该院临床分离的CRAB株存在NDM-1型金属酶,REP-PCR法分析CRAB同源性,提示该院CRAB存在水平克隆传播,A型主要流行株。

OBJECTIVE To detect the metallo-β-lactamases produced by the carbapenem-resistant Acinetobacter baumannii and analyze the homology among the strains.METHODS From Aug 2012 to Dec 2012,totally 51 clinical isolates of carbapenem-resistant A.baumannii were collected,then the drug susceptibility testing was performed by using VITEK-2drug susceptibility analysis system,the phenotypes of the metalloenzymes were screened with the use of EDTA disk synergy test;the metalloenzymes genes including IMP,SIM-1,VIM,and NDM-1were detected by using PCR,and the homology of the strains was analyzed by means of repeat sequence polymerasechain-reaction（REP-PCR）.RESULTS Totally 51 strains of carbapenem-resistant A.baumannii were resistant to multiple antibiotics.The EDTA disk synergy test showed that there was only one strain tested positive for metalloenzymes with the positive rate of 1.96%.The PCR test indicated that among the 51 strains of carbapenem-resistant A.baumannii,only one strain carried with NDM-1gene,while the IMP,SIM-1,or VIM gene was not found.The 51 strains of carbapenem-resistant A.baumannii could be divided into 4genotypes（A-F）,including 48（94.12%）strains of genotype A（the major prevalent strains）,1strain of genotype B,1strain of genotype C,and 1strain of genotype D.CONCLUSIONThe clinical isolates of carbapenem-resistant A.baumannii in the hospital are confirmed to produce NDM-1type metalloenzymes.The REP-PCR analysis of the homology of the carbapenem-resistant A.baumannii strains indicates that the horizontal cloning spread exits among the carbapenem-resistant A.baumannii strains and that the genotype A strains are the predominant prevalent strains.