鸡源大肠杆菌四环素耐药基因检测

Detection of Tetracycline-tolerant Genes in Escherichia coli Isolated from Chickens

用肉汤稀释法测定32株鸡源大肠杆菌对四环素等8种抗菌药物的敏感性,用PCR方法检测5种四环素耐药基因(tet基因),并用ERIC-PCR方法分析试验菌株间的克隆关系。结果显示:32株大肠杆菌对四环素、多西环素的耐药率分别为84%、75%,tetA和tetB阳性率分别为78%和25%。总tet基因阳性率为90.6%,与对四环素、多西环素的耐药率基本一致。携带1种或2种tet基因的临床分离菌,不仅对四环素类药物耐药,还对头孢噻肟、环丙沙星、新霉素和氟苯尼考耐药,呈现多重耐药的特点。试验菌共分为A^O 15个ERIC型,tetA和tetB几乎均匀分布于不同ERIC型菌株中,表明其在试验菌株间水平扩散。

The susceptibilities of 32 strains of Escherichia coli isolated from chickens to 8 antibacterial agents were determined with broth microdilution method, the presence of 5 tetracycline -tolerant genes （tet genes） was investigated by using PCR method, and the clonal relationship among the tested isolates was assessed by using ERIC - PCR method. The results revealed that the toler- ant rates of 32 isolates to tetracycline and doxycycline were 84% and 75% respectively, and the positive rates of genes tetA and tetB in these strains were 78% and 25% respectively. Total positive rate of gene tet in 32 strains was 90.6%, which was basically con- sistent with the above drug - tolerant rates. The isolates carrying one or two tet genes were tolerant not only to tetracycline, but also to cefotaxime, ciprofloxacin, florfenicol and neomycin, showing multidrug tolerance. A total of 15 ERIC patterns （A - O） were ob- served among the 32 strains of E. coll. The genes tetA and tetB were found to almost equally distribute on various ERIC - pattern i- solates, indicating their horizontal spread in E. coli isolates.