川西北高原2009-2016年牦牛源大肠杆菌耐药性变迁和整合子携带分析

【目的】针对大肠杆菌耐药性呈现逐年增加的趋势和牦牛疾病防控中抗菌药物使用存在的问题，本研究对2009-2016年度采自川西北高原地区散养牦牛（包括健康和患病）的粪便、屠宰场宰杀牦牛的胃肠道内容物和病死牦牛的脏器1 908株大肠杆菌进行27种抗菌药物敏感性试验和整合酶基因检测，以了解川西北高原地区牦牛源大肠杆菌耐药性变迁规律和整合子携带情况，为牦牛安全用药提供参考。【方法】按照美国临床和实验室标准协会(NCCLS)推荐的微量肉汤稀释法对分离菌株进行最小抑菌浓度(MIC)测定，利用WHONet 5.6软件包对试验数据进行统计处理分析；采用常规PCR方法扩增Ⅰ类和Ⅱ类整合酶基因以检测分离菌株Ⅰ类和Ⅱ类整合子携带情况。【结果】2009-2016各年度分离的大肠杆菌对27个药物的耐药水平表现出逐年增高的趋势。除了2014-2016年度分离菌株对土霉素的耐药水平和2015-2016年度分离菌株对磺胺类药物的耐药水平超过60.00%外，其他年度分离菌株对其余23个试验药物的耐药水平较低，其中对乙酰甲喹和利福平的耐药率均在30.00%以下，对乙酰甲喹的敏感性高于利福平。不同年份的菌株整合子携带率也不同，788株携带至少一种类型整合子，占41.30%（788/1908），同时携带Ⅰ类整合子和Ⅱ类整合子的菌株共有140株，占7.34%（140/1908）。其中，携带Ⅰ类整合子的菌株共有582株，携带Ⅱ类整合子的菌株共有346株，分别占30.50%（582/1908）和18.13%（346/1908）。【结论】川西北高原地区牦牛源大肠杆菌的耐药性变迁和整合子携带情况分析结果，能够为大肠杆菌的流行病学研究及其防治药物的筛选提供理论依据和试验资料，保证抗菌药物在川西北地区的正确合理应用。

Vicissitude of Drug Resistance and Integron-Carrying of Escherichia coli Isolated from Yak Between 2009 and 2016 in Northwest Sichuan Plateau

【Objective】Aiming at the trend of drug resistance of Escherichia coli increased year by year and the problem of antibacterial agents for diseases control and prevention in yak (Bos grunniens), 1 908 Escherichia coli isolates from feces of free-ranging yaks (including the healthy and ill yaks), gastrointestinal contents (slaughtered yaks) and viscera samples (dead yaks) were chosen for antimicrobial susceptibility testing to 27 antibacterial agents and integrase genes detection between 2009 and 2016 in this study. The results of the study will be helpful to investigation of the vicissitude of drug resistance and integron-carrying of Escherichia coli isolated from yak and provide a reference for safe medication for yak in northwest Sichuan plateau.【Method】Broth microdilution method and WHONet5.6 software were used, respectively, for minimum inhibitory concentration (MIC) determination according to the guidelines of Clinical and Laboratory Standards Institute (NCCLS) and the experimental data statistical analysis. Class 1 and class 2 integrase genes were amplified using conventional PCR for the detection of integron-carrying of class 1 and class 2 integrons. 【Result】 The results showed that: the drug resistance level to 27 antibacterial agents of the strains isolated between 2009 and 2016 kept a rising trend year by year. Except that the drug resistance level to oxytetracycline of the strains isolated between 2014 and 2016 and the drug resistance level to sulfonamides of the strains isolated between 2015 and 2016 were over 60.00%, all the other strains isolated in different years revealed lower drug resistance level to other 23 antibacterial agents and the drug resistance level to mequindox and rifampicin were lower than 30.00%, and the drug resistance rate to mequindox was lower than rifampicin between 2009 and 2016. Integron-carrying rate of Escherichia coli isolated in different years was different, 774 isolates carried at least one type of integron, accounting for 41.30% (788/1908) and 140 isolates carried both class 1 and class 2 integron, accounting for 7.34% (140/1908). Of which, 582 isolates carried class 1 integron and 346 isolates carried class 2 integron, accounting for 30.50% (582/1908) and 18.13% (346/1908), respectively.【Conclusion】The results of vicissitude of drug resistance and integron-carrying of Escherichia coli isolated from yak between 2009 and 2016 in northwest Sichuan plateau could provide a theoretical basis and experimental data for epidemiology study and screening for preventive drugs and ensure the reasonable application of antibacterial drugs in northwest Sichuan plateau.