鸡源大肠埃希菌的耐药性与分子分型研究

Study on Antimicrobial Resistance and Molecular Subtyping of Escherichia coli Isolated from Chickens

关键词:  大肠埃希菌  耐药性  PFGE  RP分型  分子分型

Key words:  Escherichia coli  antimicrobial resistance  PFGE  Ribotyping  molecularsubtyping

摘要:

为了解目前规模化养殖厂鸡源大肠埃希菌的耐药性以及分子流行规律和特征，为该菌的分子溯源及风险评估提供依据，本研究收集2013～2014 年的鸡源大肠埃希菌共计741株，采用微量稀释肉汤法分别对常用的9 类13 种抗菌药物进行药物敏感性测定，以了解大肠埃希菌的耐药表型。在筛选出多重耐药严重的菌株后，同时采用脉冲场凝胶电泳（PFGE）分型方法及核糖体（RP）分型方法进行分子分型分析。结果显示，2013～2014年所分离的鸡源大肠埃希菌对氨苄西林、阿莫西林/克拉维酸、大观霉素、四环素、多西环素、氟苯尼考、磺胺异噁唑、复方新诺明、氧氟沙星和恩诺沙星的耐药率较高，在50 %以上，且主要为多重耐药菌株。用Xba Ⅰ酶切后进行PFGE分析，结果表明，29株鸡源大肠埃希菌可分为22个带型；用EcoRⅠ酶切之后，RP聚类分析结果表明，鸡源大肠埃希菌分为14个带型。鸡源大肠埃希菌耐药率较高，表现出较为严重的耐药性，同一分型菌株的耐药谱型并非完全一致，菌株基因型呈多态性。

Abstract:

This study was conducted to investigate the antimicrobial resistance and obtain the subtyping of Escherichia coli isolated from chickens. 741 strains of Escherichia coli were collected from different areas in Shanghai in two years (2013-2014). Susceptibility test to 13 antimicrobial agents was performed by broth microdilution. Pulsed-field gel electrophresis(PFGE)and Ribo-printer(RP) were used to subtype the multidrug resistant strains. According to the antimicrobial susceptibility test of Escherichia coli, the resistance rates to ampicillin, amoxicillin / clavulanic acid, spectinomycin, tetracycline, doxycycline, florfenicol, sulfonamide isoxazole, trimenthoprim-sulfamethoxazole, ofloxacinand enrofloxacin were generally high.. And more than 80% multidrug resistant strains were detected. Results of PFGE showed that these strains of Escherichia coli were divided into 22 types after digested by XbaⅠ. While results of RP divided these strains into14 types after digested by EcoRⅠ. Compared with RP, PFGE had higher definition on molecular subtyping. This study showed that the genetype of E. coli was polymorphic. And phenotypes of isolates with the same subtyping were not exactly identical.