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.coli.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.%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。
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