大肠埃希菌产超广谱β-内酰胺酶基因型与耐药相关性分析

Genotypes of extended spectrum β-lactamases in escherichia coli and relations with antibacterial drugs

关键词:  大肠埃希菌  超广谱β－内酰胺酶  基因分型  耐药性

Key words:  escherichia coli  extended spectrumβ-lactamases  genotype  drug resistance

摘要:

［目的］对临床分离的大肠埃希菌产超广谱β内酰胺酶（extended-spectrum β-lactamases，ESBLs）株的发生率、基因类型及其对抗菌药物的耐药相关性进行分析，为临床治疗产ESBLs大肠埃希菌感染提出建议。［方法］常规分离临床标本，经API系统鉴定。按照NCCLs推荐的纸片扩散法表型确证实验进行ESBLs检测。采用PCR方法对细菌进行耐药基因扩增。采用二倍琼脂稀释法测定抗菌药物对所有菌株的最低抑菌浓度（MIC）。［结果］84株大肠埃希菌中产ESBLs30株，占35.71％。30株表型确证实验ESBLs阳性菌中，23株菌有至少一组引物扩增呈阳性。基因型构成以CTX-M型为主。最低抑菌浓度结果，产ESBLs大肠埃希菌对亚胺培南敏感率为100%；对含酶抑制剂的复合β-内酰胺类抗菌药物哌拉西林/他唑巴坦敏感率为76.67％；对头孢噻肟的耐药率为83.33％,对头孢他啶耐药率为46.67％。［结论］本实验ESBLs产生株基因型以CTX-M型为主,其对含酶抑制剂的复合β－内酰胺类抗菌药物哌拉西林/他唑巴坦相对敏感，对头孢他啶耐药率比头孢噻肟相对低，亚胺培南是最敏感的抗菌药物。

Abstract:

［Objective］To investigate the prevalence of Extended spectrum β-lactamases in clinical isolates of Escherichia coli ，the genotypical characteristics and the relations with antibacterial resistance of ESBLs.［Methods］Escherichia coli were isolated from clinical specimens, and identified by API system. The ESBLs producing strains were detected by K-B disc diffusion method phenotypic confirmatory test which was recommended by NCCLS(National Committee for Clinical Laborary Standards).PCR were performed using primers specific for blaCTX-M-1, blaCTX-M-9, blaSHV, blaTEM. MIC (minimal inhibitory concentration) of 12 kinds of antibacterial drugs were detected with double agar dilution method.［Results］In this experiment, 30 of the 84 strains (35.71%) of Escherichia coli produced ESBLs. The 30 ESBLs producing strains were amplificated by four groups of primers, and 23 strains were positive at least one group of primers. It was minly type that were blaCTX-M. blaCTX-M was minly type .MIC results showed the sensitivity of ESBLs producing strains to imipenem, it's 100%.and the susceptibility rate to piperacillin/ tazobactam was 76.67%.The resistance rate to cefotaxime was 83.33%, the resistance rate to ceftazidime was 46.67%.［Conclusions］The ESBLs producing rate in Escherichia coli , CTX-M is the prevalent genotype of ESBLs. ESBLs producing strains had higher resistance rate to cefotaxime than to ceftazidime. There had obviously inhibition of piperacillin/tazobactam to ESBLs producing strains. Imipenem is the most effective antibiotics to infections caused by ESBLs producing strains.