多药耐药大肠埃希菌携带CTX-M-14与CTX-M-15酶基因的研究

Multidrug resistant Escherichia coli carrying genes of CTX-M-14 and CTX-M-15

目的了解多药耐药大肠埃希菌携带质粒介导的CTX-M-14与CTX-M-15酶基因分布及其对常见抗菌药物的耐药性,为临床合理选择抗菌药物提供依据。方法收集2007年7月-2008年7月感染患者送检标本中分离出的大肠埃希菌71株,采用纸片扩散法(K-B法)对其中多耐30株、双耐19株及单耐16株大肠埃希菌进行药物敏感试验,提取质粒DNA,以此为模板采用聚合酶链反应(PCR)法对CTX-M-14与CTX-M-15酶基因进行扩增,PCR产物送上海生工进行基因测序。结果 71株大肠埃希菌耐药模式为多耐30株、双耐19株、单耐16株、全敏6株,分别占42.2%、26.8、22.5%、8.5%;56株多药耐药大肠埃希菌对亚胺培南、阿米卡星的耐药率较低,<15.0%,对头孢噻肟、氨曲南、庆大霉素等的耐药率均>50.0%;56株多药耐药大肠埃希菌中,44株检出CTXM-14酶基因,28株检出CTX-M-15酶基因,检出率分别为78.6%和50.0%;携带CTX-M-14与CTX-M-15酶基因的多药耐药大肠埃希菌对头孢噻肟、头孢他啶的耐药率分别81.8%、52.2%和96.4%、60.7%,两者相比较,差异有统计学意义(P<0.01)。结论多药耐药大肠埃希菌中,含CTX-M-14与CTX-M-15酶基因菌株是常见的,携带CTX-M-14与CTX-M-15酶基因的多药耐药大肠埃希菌对头孢噻肟耐药率高于头孢他啶。

OBJECTIVE To explore the distribution of multidrug resistant Escherichia coli carrying genes of CTXM-14 and CTX-M-15 and drug resistance to common antibacterial agents,so as to provide guidance for rational use of antibacterial agents.METHODS A total of 71 strains of E.coli were isolated from the submitted samples of infection patients from Jul.2007 to Jul.2008,in which 25 strains of multidrug resistance,15 strains of double drug resistance and 16 strains of single drug resistance were given drug sensitivity test by Kirdy-Bauer（K-B）.The plasmid DNA was extracted,which was used as a template to augment CTX-M-14 and CTX-M-15 genes.PCR products were sent to Shanghai Biotechnology Co.for gene sequencing.RESULTS The template of drug resistance for the 71 strains of E.coli were 30 strains of multidrug resistance,19 strains of double drug resistance,16 strains of single drug resistance and 6strains of all drug sensitivity,accounting for 42.2%,26.8,22.5% and 8.5%,respectively.The 56 strains of multidrug resistant E.coli had low drug resistance rate to imipenem and amikacin,〈15.0%,but to cefotaxime,aztreonam and gentamicin 〉50.0%.CTX-M-14 gene had been inspected from 44 strains and CTX-M-15 gene 28strains,within the 56 strains of multidrug resistant E.coli,accounting to 78.6%and 50.0% respectively.The drug resistance rate for multidrug resistant E.coli carrying genes of CTX-M-14 and CTX-M-15 gene to cefotaxime and ceftazidime were 81.8%,52.2% and 96.4%,60.7%respectively,which had significant differences（P〈0.01）.CONCLUSIONIt is common to see the strains carrying CTX-M-14 and CTX-M-15 gene in multidrug resistant E.coli,and the multidrug resistant E.coli carrying CTX-M-14 and CTX-M-15 gene has higher drug resistance to cefotaxime than ceftazidime.