摘要目的 调查大肠埃希菌尿液分离株中β-内酰胺酶基因、AmpC酶基因和膜孔蛋白ompC基因的存在和变异情况.方法 对宁波市第一医院2008年10月至2009年3月患者尿液样本中分离的大肠埃希菌(28株)采用PCR及序列分析的方法,分析15种β-内酰胺酶基因、6种AmpC酶基因和膜孔蛋白ompC基因.结果 28株大肠埃希菌仅对美罗培南和亚胺培南100％敏感.所有分离菌中检出广谱β-内酰胺酶基因以TEM-1-like为主,共17株(60.7％)、超广谱β-内酰胺酶基因以CTX-M-55-like为主,共6株(21.4％)；AmpC酶基因CMY-2-like 3株(10.7％)；均检出膜孔蛋白ompC基因,且均存在变异.本组菌中TEM-1-like、CTX-M-55-like、CMY-2-like和ompC均阳性2株,3种基因同时阳性5株,2种基因同时阳性16株,只检出1种基因5株.菌株亲缘性分析显示,28株大肠埃希菌多耐药中多数菌株已发生演化,只有1号和22号株、14号和15号株这两组携带相同基因.结论 本组大肠埃希菌中,β-内酰胺酶基因、AmpC酶基因、ompC基因均有检出,这些基因是菌株对β-酰胺类抗菌药物产生耐药的重要原因.菌株基因多态性明显.

abstractsObjective To investigate the distribution and variety of beta-lactamase genes,AmpC genes and ompC gene (outer membrane porin protein C) in E.coli strains isolated from urine.Methods From October 2008 to March 2009,28 strains of E.coli isolated from urine were collected from Ningbo First Hospital.Fifteen kinds of beta-lactamase genes,6 kinds of AmpC genes,and ompC gene were analyzed by PCR and verificated by DNA sequencing.Results Twenty-eight strains of E.coli were all sensitive to imipenem and meropenem( 100％ ).In all the strains,the main broad-spectrum β-lactamase TEM-1-like gene was detected in 17(60.7％ ) strains the main extended-spectrum β-lactamase CTX-M-55-like gene was detected in 6 (21.4％) strains; AmpC gene CMY-2-like was detected in 3 (10.7％)strains by DNA sequencing,respectively.ompC gene was detected in all the 28 strains,and all had mutations.Two strains were with TEM-1-like,CTX-M-55-like,CMY-2-like,ompC genes all positive,5 strains were with 3 genes positive,16 strains were with 2 genes positive and 5 strains were with 1 gene positive.Phylogenetic analysis showed that 28strains of multi-resistant E.coli revealed gene polymorphism,and most strains showed sequence evolution.Only strain 1and 22,strain 14 and 15 were the same clone and carried the same genes.Conclusions Beta-lactamase genes,AmpC genes,and ompC gene are all detected in this group of E.coli strains,and these positive genes play a key role in resistance to beta-lactam antimicrobial gents.The gene polymorphism of these strains is obvious.