中文摘要：

抗生素抗性菌的扩散已成为全世界面临的重要公共卫生安全隐患.本文从某城市污水处理厂二级出水中分离出21株四环素抗性菌,对其种属、生理生化特性、抗生素耐受性进行了研究.结果表明,21株四环素抗性菌均属于肠杆菌科,分别属于气单胞菌属（9株）、埃希氏菌属（5株）、肠杆菌属（3株）、克雷伯氏菌属（2株）、柠檬酸杆菌属（1株）和哈夫尼菌属（1株）.这些菌大多属于条件致病菌,且有18株携带质粒.21株四环素抗性菌中,气单胞菌、埃希氏菌的平均最大生长量显著高于肠杆菌,大部分菌株的迟滞时间在2 h以内.抗生素耐受性试验结果表明,四环素抗性菌对氯霉素耐受能力最强,对β-内酰胺酶类抗生素（青霉素、氨苄青霉素、头孢噻吩）的耐受性次之,对利福平的耐受性最弱.75%以上的四环素抗性菌同时表现出对其它5种抗生素具有抗性.以上结果为我国污水处理厂抗生素抗性菌的风险分析与控制提供了参考数据.

英文摘要：

Antibiotic-resistant bacteria becomes a concern of public health worldwide. In this study,21 strains of tetracyline-resistant bacteria（ TRB）were isolated from secondary effluent of a municipal wastewater treatment plant. The 21 strains of TRB were identified and classified into different genera.Their growth characters and antibiotic resistance were also investigated. The results showed that all the TRB in the secondary effluent belonged to the family of Enterobacteriaceae and most of them are opportunistic pathogens harboring plasmids. Ordered by the number of strains,they belonged to genus of Aeromonas（ 9 strains）,Escherichia（ 5 strains）,Enterobacter（ 3 strains）,Klebsiella（ 2 strains）,Citrobacter（ 1 strain） and Hafnia（ 1 strain）. Among these TRB,Aeromonas and Escherichia had higher average maximum biomass compared with Enterobacter and most TRB had lag phase times lower than 2hours. Based on results of antibiotic resistance test,TRB had the highest resistance to chloramphenicol,middle resistance to penicillin,ampicillin,cephalothin,and the lowest resistance to rifampicin. 75% of TRB showed resistances to other 5 antibiotics according to CLSI standard. The results in this study provided fundamental data for risk analysis and control of TRB emitted from wastewater treatment plants.