河南地区猪源肠外致病性大肠杆菌的分离鉴定与耐药性试验

Identification and Antimicrobial Resistance of Extraintestinal Pathogenic Escherichia coli Isolates from Pigs in Henan Province

为了解猪源肠外致病性大肠杆菌在河南地区的流行及耐药性,本试验于2016—2018年从河南省61家猪场送检的发病猪中,采集肺脏等病料,进行大肠杆菌的分离与鉴定,并用微量稀释法测定分离菌株的耐药性,采取PCR法检测分离菌株中氟苯尼考耐药基因(floR)、Ⅰ类整合酶基因的携带情况,通过Ⅰ类整合子基因盒可变区序列的BLAST比对,分析其耐药基因携带情况。结果显示,经细菌分离共获得17株肠外致病性大肠杆菌,检出率为27.86%(17/61);分离菌株对氨苄西林、磺胺甲噁唑、四环素、氟苯尼考和氯霉素等药物耐药率为100%,对多黏菌素耐药率为41.18%,分离菌株均呈多重耐药;在分离菌株中,floR、Ⅰ类整合子携带率均为100%,Ⅰ类整合子基因盒主要携带dfrA17-aadA5、aadA22-aadA23-aadA25、dfrA12、dfrA12-aadA2和floR等类型耐药基因谱。本试验结果表明河南地区猪源肠外致病性大肠杆菌具有一定的流行性,且耐药问题十分严重,极易导致临床上治疗失败,应引起重视。

This study investigated the prevalence and antimicrobial resistance of porcine extraintestinal pathogenic Escherichia coli in Henan province.Samples of lungs and other tissues were collected from diseased pigs from 61 pig farms in Henan province for isolation and identification of E.coli during 2016—2018.Antimicrobial resistance of E.coli isolates was determined by microdilution method.Florfenicol resistance gene(floR)and class I integrase gene in E.coli isolates were detected by PCR.Variable region sequences in class I integron gene cassettes were analyzed for drug resistance by BLAST.The results indicated that 17 extraintestinal pathogenic E.coli isolates were recovered by bacterial isolation,with positive rate of 27.86%(17/61);these isolates were fully resistant(100%)to ampicillin,sulfamethoxazole,tetracycline,florfenicol,chloramphenicol and other drugs,and partially resistant(41.18%)to polymyxin;and all isolates were multidrug resistant.The detection rates of floR and class I integron were 100%in the isolates;and class I integron gene boxes mainly carry dfrA17-aadA5,aadA22-aadA23-aadA25,dfrA12,dfrA12-aadA 2,and floR.Thus,porcine extraintestinal pathogenic E.coli is prevalent in Henan province,and displays multidrug resistance,which can easily lead to clinical treatment failure,and requires particular attention for its prevention and control in pigs.