广泛耐药鲍曼不动杆菌产碳青霉烯酶基因型和表型分析

Genotypic and phenotypic analysis of carbapenemase from extensively drug-resistant Acinetobacter baumannii

目的分析临床分离的鲍曼不动杆菌耐药谱和产碳青霉烯酶表型和基因型。方法应用全自动细菌鉴定仪对从本地三级医院收集的93株鲍曼不动杆菌进行菌株鉴定和药敏试验,用碳青霉烯酶抑制法(carbapenem inactivation method,CIM)检测产碳青霉烯酶鲍曼不动杆菌耐药表型;PCR法确定产碳青霉烯酶菌株耐药基因型。结果93株鲍曼不动杆菌,广泛耐药株47株(耐药率为50.5%),耐碳青霉烯类56株(耐药率为60.2%)。以亚胺培南为底物的碳青霉烯酶抑制法检出产碳青霉烯酶鲍曼不动杆菌55株,检出率为98.1%(55/56)。在56株碳青霉烯类耐药株中,TEM-1基因、PER-1基因、OXA-23基因、Ⅰ型整合子基因、adeB基因阳性率分别为75.0%、42.9%、80.4%、73.2%、64.3%,其余耐药基因均未检出。结论碳青霉烯酶抑制法快速、简便,可以作为常规检测产碳青霉烯酶鲍曼不动杆菌的表型检测方法;目前本地OXA-23和TEM-1型碳青霉烯酶以及Ⅰ型整合子是导致鲍曼不动杆菌广泛耐药和对碳青霉烯酶类耐药的主要原因。

Objective To investigate the drug resistant spectrum and carbapenemase-resistant phenotype and genotype in clinical isolates of Acinetobacter baumannii.Methods Identification and susceptibility to antimicrobial agents of the 93 clinical A.baumannii strains were tested by VITEK compact.Carbapenem inactivation method(CIM)was applied to detect the carbapenemase in the A.baumannii strains.Carbapenemase-encoding genes were determined by PCR.Results Forty-seven of the 93 strains were extensively drug-resistant strains and 56 strains showed resistance to carbapenem drugs.The sensitivity of CIM was 98.1%in detecting carbapenemase-producing A.baumannii with imipenem.Of the 56 carbapenem-resistant A.baumannii isolates,the positive rate of resistance gene was respectively 75.0%of TEM-1,42.9%of PER-1,80.4%of OXA-23,73.2%of class 1 integron gene,and 64.3%of adeB gene.Other genes were not detected.Conclusion Carbapenem inactivation method is a cost-effective method and easier to operate.OXA-23 and TEM-1 type carbapenemase and classⅠintegron may be the main causes of extensive-resistance and resistance to carbapenemase of A.baumanii.