摘要目的：研究大肠埃希菌对碳青霉烯类抗生素的耐药机制及分子分型。方法2007-2011年从杭州市3家医院分离到22株对碳青霉烯类抗生素不敏感的大肠埃希菌。琼脂稀释法测定抗生素最低抑菌浓度（ MIC）；接合试验、PCR扩增和序列分析等研究细菌对碳青霉烯类抗生素耐药的分子机制。脉冲场凝胶电泳（PFGE）、多位点序列分型（MLST）和系统发育分型（phylogenetic typing）等对菌株进行分子分型。结果22株大肠埃希菌亚胺培南和美罗培南的MIC范围为1～16μg/ml，厄他培南为2～64μg/ml。所有菌株产KPC-2型碳青霉烯酶及各种β-内酰胺酶，部分菌株同时产质粒介导的AmpC酶。22株大肠埃希菌均可通过接合试验或转化试验将碳青霉烯耐药性传递给大肠埃希菌EC600，使后者获得blaKPC-2基因及与供体菌相似的耐药性。 PFGE显示仅少数菌株为相同克隆或密切相关；MLST显示最常见的序列类型为ST131（9株）和ST648（5株）， ST38和ST405各2株；系统发育分析显示9株ST131菌株均为B2群，另有11株属于D群，B1群和A群各1株。结论杭州地区产KPC-2大肠埃希菌主要为世界范围流行的多重耐药菌株ST131，其次为ST648。

abstractsObjective To investigate the molecular types of carbapenem-non-susceptible Esche-richia coli ( E.coli) isolates and their mechanism of carbapenem resistance .Methods Twenty-two carbap-enem-non-susceptible E.coli strains were isolated from 3 hospitals in Hangzhou from 2007 to 2011.The mini-mum inhibitory concentrations ( MICs) of antimicrobials to those isolates were determined by agar dilution method and E-test.The molecular mechanisms of carbapenem resistance of E.coli isolates were analyzed by conjugation experiment,PCR and DNA sequencing.Pulsed-field gel electrophoresis (PFGE),multilocus se-quence typing ( MLST ) , and phylogenetic typing were performed to analyze the molecular epidemiology of those isolates.Results The MICs of imipenem and meropenem to 22 E.coli isolates were ranged from 1 μg/ml to 16 μg/ml,and the MICs of ertapenem were 2 μg/ml to 64 μg/ml.All E.coli isolates produced the KPC-2 carbapenemase and various β-lactamases , and some of them also produced plasmid-mediated AmpC enzymes.Carbapenem resistance was transferred by conjugation and transformation from 22 E.coli iso-lates to E.coli EC600 strains.The E.coli transconjugants or transformants acquired the blaKPC-2 gene and showed similar antibiotic susceptibility patterns in comparison with donor strains .Only a few isolates were in-distinguishable or closely related as indicated by PFGE .Four sequence types including ST131 (9 isolates), ST648 (5 isolates),ST38 (2 isolates) and ST405 (2 isolates) were identified by MLST.Phylogenetic analy-sis indicated that 9 ST131 isolates belonged to phylogenetic group B 2 and the other isolates belonged to group D (11 isolates),group B1 (1 isolate) and group A (1 isolate),respectively.Conclusion The sequence type of prevalent E.coli isolates producing KPC-2 from Hangzhou was ST131,which is an international epi-demic,multidrug-resistant clone,followed by ST648.