山东省携带bla_(NDM-5)基因大肠埃希菌的分子流行病学研究

Study on Molecular Epidemiology of NDM-5-Producing Escherichia coli Isolates in Shandong Province,China

目的调查山东省携带bla_(NDM-5)基因大肠埃希菌医院分离株的分子流行病学特点,为医院感染预防和控制提供理论依据。方法收集山东省3家医院2015年3月-2016年12月临床分离的20株对亚胺培南耐药的大肠埃希菌。菌株的鉴定和药敏通过法国梅里埃Vitek-2 Compact系统重新进行。PCR筛选携带bla_(NDM-5)基因的大肠埃希菌,然后对菌株携带的其他碳青霉烯酶、超广谱β-内酰胺酶、氨基糖苷和喹诺酮类耐药相关基因进行扩增,并测序确认。多位点序列分型和脉冲场凝胶电泳分析菌株间的同源性。结果经扩增和测序确认,11株大肠埃希菌携带bla_(NDM-5)基因,对临床常用的抗菌药物呈现多重耐药,同时每株菌还携带多个其他耐药相关基因。多位点序列分型显示以ST167型为主,共4株(36.4%,4/11),其他分别为ST617型2株(18.2%,2/11),ST46、ST453、ST448、ST6388和ST410型各1株。这11株大肠埃希菌的脉冲场凝胶电泳带型各不相同,没有呈现克隆聚集性。结论研究表明山东省3家医院都检测到携带bla_(NDM-5)基因的大肠埃希菌,以ST167型为主,且脉冲场凝胶电泳没有呈现克隆聚集性,属于散发病例。经检索,携带bla_(NDM-5)基因的ST617、ST46、ST453、ST6388和ST410型大肠埃希菌为国内外首次报道。公共卫生部门有必要加强对碳青霉烯类耐药肠杆菌的监控。

Objective To investigate the prevalence of the carbapenem-resistant Escherichia coli isolates harboring bla（NDM-5） in Shandong Province so as to provide practice guidelines for the nosocomial infection prevention and control.Methods Twenty imipenem-resistant Escherichia coli strains were collected from March 2015 to December 2016 in three hospitals in Shandong Province.The identification and antibiotic susceptibility test of these isolates were done using VITEK-2 Compact system.Polymerase Chain Reaction（PCR）and sequencing were used for screening NDM-5-Producing Escherichia coli.Then these E.coli were detected by PCR for other carbapenemases,extended-spectrum-β-lactamases and plasmid-mediated quinolone resistance（PMQR）genes,and the variants of these genes were identified by sequencing.Multilocus sequence typing（MLST）and pulsed field gel electrophoresis（PFGE）were performed to analyze the genetic relatedness.Results Out of twenty E.coli strains,eleven habored not only bla（NDM-5） carbapenemase gene but also other antimicrobial-resistant genes,and were resistant to most antibiotics available.A great diversity of MLST types was observed among NDM-5-producing E.coli isolates.The ST167 were the most prevalent（4 isolates,36.4%）,and the other sequence type（ST）were ST617（2 isolates,18.2%）,ST46,ST453,ST448,ST6388 and ST410.The eleven NDM-5-producing isolates were not categorized into same PFGE type patterns.Conclusion Our results revealed that NDM-5-producing E.coli isolates were detected in three hospital in Shandong province and the ST167 was the most prevalent and that there were no occurrence of the clonal dissemination among these isolates.To our knowledge,it is the first report in worldwide that there were a couple of sequence types,including ST617,ST46,ST453,ST448,ST6388 and ST410 among NDM-5-producing E.coli isolates.And there is an urgent need for public health administrator on strengthening the surveillance of carbapenem-resistant enterobacteriaceae.