产超广谱β-内酰胺酶大肠埃希菌的基因型分型及耐药分析

Drug resistance and genotype of extended spectrum beta-lactamases (ESBLs) producing escherichia coli strains

关键词:  超广谱β-内酰胺酶  大肠埃希菌  基因型  耐药

Key words:  extended spectrum beta-lactamase  escherichia coli  genotype  drug resistance

摘要:

［目的］ 了解大连市中心医院临床分离的产超广谱β-内酰胺酶（ESBLs）大肠埃希菌耐药基因型及耐药情况。［方法］收集该院2005年11月~2006年2月连续不重复产ESBLs大肠埃希菌40株，采用美国国家临床实验室标准化委员会推荐的表型确认方法进行筛选。在此基础上，分别用针对TEM、SHV、CTX-M-Ⅰ、CTX-M-Ⅱ、CTX-M-Ⅲ、CTX-M-Ⅳ型β-内酰胺酶基因的六对特异性引物对每株细菌进行聚合酶链反应（PCR），毛细管电泳方法检测所有产ESBLs大肠埃希菌的TEM、SHV、CTX-M基因。应用K-B纸片扩散法检测产ESBLs大肠埃希菌对临床常用抗生素的耐药性。［结果］毛细管电泳结果显示，40株产ESBLs大肠埃希菌中，仅携带一种基因型的分别为SHV型1株（2.50%），CTX-M-Ⅰ型7株(17.50%)，CTX-M-Ⅱ型7株(17.50%)，CTX-M-Ⅲ型2株(5.00%)，CTX-M-Ⅳ型4株(10.00%)。有18株（46.15%）同时携带两种或两种以上基因型，且多为CTX-M型与TEM型或SHV型共同存在；药物敏感试验结果显示，产ESBLs大肠埃希菌对β-内酰胺类抗生素均表现出较高的耐药性，对碳青霉烯类药物（亚胺培南和美洛培南）的耐药率最低。［结论］该院产ESBLs大肠埃希菌近期流行的主要基因型别为CTX-M型，而且多基因携带情况常见；碳青霉烯类抗生素是目前治疗产ESBLs大肠埃希菌最有效的药物。

Abstract:

［Objective］To investigate the antibiotic resistance and genotype of extended spectrum beta-lactamase (ESBL) producing Escherichia coli amid clinical isolates from dalian municipal central hospital.［Methods］A total of 40 ESBL producing E.coli, isolates between Nov. 2005 and Feb. 2006, were screened out by phenotype confirmatory tests according to the procedures of Committee of Laboratory Standards Institute (CLSI). ESBL genes in those producing isolates were detected by PCR with primers specific for bla_TEM , bla_SHV , bla_CTX-M-Ⅰ, bla_CTX-M-Ⅱ, bla_CTX-M-Ⅲ and bla_CTX-M-Ⅳ respectively, and then the PCR products were analyzed by capillary electrophoresis. Their antibiotic resistance was determined by K-B tests.［Results］According to capillary electrophoresis results, only 1 of the 40 strains(2.50%) was SHV carrier, 7 (17.50%) were CTX-M-Ⅰ,7(17.50%) were CTX-M-Ⅱ,2 (5.00%) were CTX-M-Ⅲ,4 (10.00%)were CTX-M-Ⅳ. 18 of the 39 strains (46.15%) carried two or more kinds of genes, and CTX-M usually combined with TEM or SHV genes. K-B tests showed these strains were higher resistant to beta-lactam antibiotics and were most susceptible to Carbapenems (imipenem and meropenem).［Conclusions］The most common ESBL type in E. coli is CTX-M. Most of the studied strains isolated from our hospital usually carry more than one type of ESBL genes. Carbapenems is the most effective antibiotic to treat infections caused by ESBL producing E. coli.