腹泻犬源大肠埃希菌耐药性以及整合子–基因盒检测研究

摘要

[目的]了解腹泻犬源大肠埃希菌Escherichia coli的耐药性以及整合子携带情况.[方法]采用K-B纸片扩散法对30株分离自腹泻犬的大肠埃希菌进行19种抗菌药物的敏感性试验;PCR检测菌株中是否携带Ⅰ、Ⅱ、Ⅲ型整合酶基因,对携带有整合酶基因的阳性菌株进一步检测sul1、qacEΔ1基因以及可变区基因盒携带情况.[结果]30株分离株对19种抗菌药物表现出不同程度的耐药性,共产生18种耐药谱,对阿莫西林、氨苄西林、四环素和多西环素的耐药性较高,耐药率分别为90.00%、83.33%、66.67%和63.33%;对其余药物耐药性较低,耐药率低于14.00%;11株分离株含有Ⅰ型整合酶基因且均携带sul1和qacEΔ1基因,未检出Ⅱ型和Ⅲ型整合酶基因;Ⅰ型整合子阳性菌株中,有2株扩增出1879 bp的耐药基因盒:dfrA12+orfF+aadA2.[结论]本次检测的腹泻犬源大肠埃希菌对抗菌药物呈不同水平的耐药性;基因盒介导的耐药性与菌株的耐药表型存在部分相关性,大肠埃希菌的耐药性与Ⅰ型整合子存在一定关系.%[Objective]To investigate the antimicrobial resistance of Escherichia coli from diarrhea dogs and the distribution of integron-gene cassettes in E.coli.[Method]The Kirby-Bauer disc diffusion method was used to test the susceptibility of 30 strains of E.coli against 19 antimicrobial agents.PCR was used to detect the integrase genes(class I,II,III)in E.coli isolates.We further detected if E.coli isolates carrying integrase genes also carried the sul1,qacEΔ1 genes and gene cassettes in variable regions.[Result]Thirty isolates showed different levels of resistance to 19 antimicrobial agents with 18 kinds of resistant spectrum.E.coli isolates had high resistance to amoxicillin, ampicillin, tetracycline and doxycycline with drug resistance rates of 90.00%, 83.33%, 66.67% and 63.33%, respectively, while had low resistance to the other antimicrobials with drug resistance rates below 14.00%.Eleven out of 30 isolates were found to carry class I integrase,sul1 and qacEΔ1 genes, and class II or class III integrase gene was not detected. Among the isolates carrying class I integrase gene,the dfrA12+orfF+aadA2 gene cassette of 1 879 bp length was successfully amplified from two isolates.[Conclusion]E.coli isolates from diarrhea dogs show different levels of resistance to antimicrobial agents. Antimicrobial resistance that mediated by gene cassettes is partially related to the resistant phenotype of E.coli. Class I integron shows a certain relationship with the antimicrobial resistance of E.coli.