大肠埃希菌临床株可移动遗传元件之遗传标记与耐药基因分析

Genetic markers of mobile genetic elements and resistant genes in Escherichia coli

目的了解大肠埃希菌临床株可移动遗传元件及耐药基因存在状况以及菌株的亲缘关系,分析耐药的遗传学背景。方法收集医院2012年1-10月住院患者痰液标本中分离的大肠埃希菌共20株,采用聚合酶链反应（PCR）法分析,可移动遗传元件的10种遗传标记、19种β-内酰胺酶基因、6种氨基糖苷类修饰酶基因、6种16S rRNA甲基化酶基因,并对检测结果作样本聚类分析。结果 20株大肠埃希菌均检出可移动遗传元件之遗传标记、β-内酰胺酶基因与氨基糖苷类修饰酶基因;共检出可移动遗传元件的7种遗传标记、3种β-内酰胺酶基因、3种氨基糖苷类修饰酶基因,且耐药基因的阳性率很高,但16SrRNA甲基化酶基因未检出;traA、trbC、tnp513、IS26、IS903、ISEcp1、intⅠ1、blaTEM、blaCTX-M-1群、blaOXA-1群、aac（6＇）-Ⅰb、aadA5和aph3′-Ⅰ阳性率分别为95.0%、65.0%、30.0%、100.0%、50.0%、90.0%、100.0%、85.0%、100.0%、25.0%、40.0%、85.0%和5.0%;可移动遗传元件之遗传标记与耐药基因可分为14种阳性模式,样本聚类分析提示菌株可分A与B两群,A群中1、4、17～19号株,14～18、2、12～13号株为3个独立的克隆。结论 20株大肠埃希菌耐药表型与β-内酰胺酶基因与氨基糖苷类修饰酶基因检测结果相符,该组菌株存在医院感染的可能。

OBJECTIVE To investigate the distribution of genetic markers of mobile genetic elements and resistant genes in Escherichia coli and their relationships so as to analyze the genetic settings of resistance .METHODS From Jan .to Oct .2012 ,20 strains of E .coli were collected from sputum of inpatients in the hospital .Then ,10 kinds of genetic markers of mobile genetic elements ,19 kinds of beta‐lactamase genes ,6 kinds of aminoglycoside modif‐ying enzyme genes ,and 6 kinds of 16SrRNA methyltransferase genes were analyzed by PCR .And the sample cluster analysis was performed .RESULTS Genetic markers of mobile genetic elements ,beta‐lactamase genes ,and aminoglycoside modifying enzyme genes were positive in every strain .Totally 7 kinds of genetic markers of mobile genetic elements ,3 kinds of beta‐lactamase genes ,and 3 kinds of aminoglycoside modifying enzyme genes were positive ,and positive rates were high ,but 16S rRNA methyltransferase gene was negative .In addition ,14 kinds of positive modes were identified .The sample cluster analysis suggested that strains can be divided into cluster A and B .Strains No .1-4-17-19 ,14-18 ,2-12-13 in cluster A belonged to 3 separate clones .CONCLUSION Resistant phenotypes of 20 strains of E .coli were identical with beta‐lactamase genes and aminoglycoside modif‐ying enzyme genes .Nosocomial infections causing by this group of strains might occur .