产新德里1型金属β-内酰胺酶鲍曼不动杆菌的耐药性分析及传播机制

摘要

Objective To study the drug resistance and transmission mechanism of New Delhi metallo-β-lactamase-1 (NDM-1)-producing Acinetobacter baumannii.Methods Four hundred and forty strains of carbapenem-resistant Acinetobacter baumannii isolated from clinical specimens in the First Affiliated Hospital of Nanchang University from January 2013 to January 2015 were col-lected in this study.These strains were identified by using VITEK-2 Compact automatic system. The strains producing carbapenemases were screened using the modified Hodge test,and the blaNDM-1 gene was sequenced.The sequencing results were compared with BLAST.Further-more,strains were genotyped using the enterobacterial repetitive intergenic consensus sequence--PCR (ERIC-PCR).Plasmid conj ugation was performed in positive stains,and PCR was carried out to confirm the carbapenem-resistance genes.Plasmid profile and restriction endonuclease finger-printing were used to analyze the transmission mechanism of NDM-1-producing Acinetobacter baumannii.Results Among the 440 carbapenem-resistant isolates,11 (2.5%)were identified as the NDM-1-producing Acinetobacter baumannii,and each of them was resistant to multiple antibi-otics and harboured several resistant genes.The blaCTX-M,blaTEM,blaSHV,qnrB,qnrS,acc (6′)-Ib,rmtB and armA were the prevalent drug resistance genes.Plasmid conjugation was completedsuccessfully in 2 of the 11 blaNDM strains.Plasmid profile analysis showed blaNDM-1gene was located on a 46 kb plasmid.Conclusion Multiple resistant genes were identified in NDM-1-producing Acinetobacter baumannii isolated in the First Affiliated Hospital of Nanchang University.Among them,the blaNDM-1 gene was carried by the plasmid and transferred by conjugation.The clonal spread of NDM-1-producing Acinetobacter baumannii resulted in the transmission between strains.%目的 研究产新德里1型金属β-内酰胺酶(NDM-1)鲍曼不动杆菌的耐药性及传播机制.方法 收集南昌大学第一附属医院2013年1月至2015年1月各种临床标本中分离碳青霉烯类抗生素耐药的鲍曼不动杆菌440株作为实验菌株,采用法国梅里埃VITEK 2 compact全自动细菌鉴定仪对菌株进行鉴定及药物敏感性分析;采用改良的Hodge试验筛选产碳青霉烯酶阳性菌株,同时对试验菌株的blaNDM-1基因进行测序,测序结果BLAST比对分析;采用肠杆菌科基因间重复一致序列聚合酶链反应(ERIC-PCR)对菌株进行基因分型;对阳性株进行质粒接合试验,并对接合后菌株提取DNA进行PCR扩增检测其耐药基因,运用质粒图谱和质粒酶切图谱研究其传播机制.结果 440株碳青霉烯类耐药鲍曼不动杆中检出NDM基因阳性率为2.5%(11/440),经测序确认为blaNDM-1基因.阳性菌株呈现多重耐药现象,且每株菌均携带多种耐药基因,其中blaCTX-M、blaTEM、blaSHV、qnrB、qnrS、acc(6′)-Ib、rmtB、armA等为最常见共同携带耐药基因.11株blaNDM-1基因阳性菌质粒接合试验成功2株,采用PCR技术扩增接合成功菌株的blaNDM-1基因.质粒图谱分析发现blaNDM-1基因位于一大小约46 kb质粒上.结论 南昌大学第一附属医院产NDM-1)型鲍曼不动杆菌携带多种耐药基因,其中blaNDM-1基因主要位于质粒上,可通过接合方式传播,存在克隆传播现象,易于在菌株间流行.