天津农学院学报 ›› 2023, Vol. 30 ›› Issue (5): 23-29.doi: 10.19640/j.cnki.jtau.2023.05.005

• 研究与简报 • 上一篇    下一篇

鸡源大肠杆菌的分离鉴定及其致病性分析

陈家乐1, 何金灵1, 杜荣起1, 李丹若1, 金天明2,通信作者, 张东超1,通信作者   

  1. 1.天津农学院 动物科学与动物医学学院 天津市农业动物繁育与健康养殖重点实验室,天津 300392;
    2.天津市农业科学院,天津 300192
  • 收稿日期:2022-08-26 出版日期:2023-10-31 发布日期:2023-12-22
  • 通讯作者: 张东超(1991—),男,讲师,博士,主要从事人兽共患病分子病原学与免疫学研究。E-mail:zdc2991@163.com。金天明(1968—),男,教授,博士,主要从事分子免疫病理学研究。E-mail:jtm680@163.com。
  • 作者简介:陈家乐(1999—),女,本科在读,主要从事畜禽疾病诊断研究。E-mail:cjl102199@163.com。
  • 基金资助:
    天津市教委科技计划项目(2019KJ032); 天津市农业动物繁育与健康养殖重点实验室开放基金课题(2020zdkf02); 国家自然基金项目(31572492); 天津市研究生科研创新项目(2021YJSS137); 天津市大学生创新训练计划项目(202010061046); 天津市兽医生物技术科研创新团队资助项目(TD12-5019)

Isolation, identification, and pathogenicity analysis of Escherichia coli in chicken

Chen Jiale1, He Jinling1, Du Rongqi1, Li Danruo1, Jin Tianming2,Corresponding Author, Zhang Dongchao1,Corresponding Author   

  1. 1. Tianjin Key Laboratory of Agricultural Animal Breeding and Healthy Husbandry, College of Animal Science and Veterinary Medicine, Tianjin Agricultural University, Tianjin 300392, China;
    2. Tianjin Academy of Agricultural Sciences, Tianjin 300192, China
  • Received:2022-08-26 Online:2023-10-31 Published:2023-12-22

摘要: 天津某规模化鸡场出现一批疑似大肠杆菌(Escherichia coli,E. coli)感染的病鸡,为分离该鸡病的病原菌并分析其致病性,研究通过临床综合诊断、病料采集、细菌分离培养、鉴别培养基和生化鉴定、16S rRNA检测、系统进化树与同源性分析、药敏试验、毒力基因检测、小鼠致病性试验及病理组织学观察等综合分析。结果显示,临床剖检可见典型的腹膜炎、肝周炎、心包炎等症状;分离菌株革兰氏染色为阴性短小杆状菌,培养基和生化鉴定结果与大肠杆菌的生长特性一致;16S rRNA特异性引物PCR扩增和系统进化树及同源性分析发现,分离菌株与大肠杆菌亲缘关系为同一分支,同源性高达99.99%以上;药敏试验显示该分离菌株对氟苯尼考高度敏感,对四环素、多西环素中度敏感;PCR扩增出fimChlyFompTiroN 4种大肠杆菌毒力基因;动物致病性试验中接种分离菌株的小鼠在16 h内全部死亡,且在小鼠肝脏和血液中均检测到细菌;病理组织学观察发现感染小鼠的肝脏、心脏、肺脏、肾脏、脾脏以及肠道均受到不同程度损伤。研究结果表明,该病鸡分离菌株为大肠杆菌,且该菌株具有多重耐药性并携带多种毒力基因,对动物有较强的致病力。研究结果为鸡场防控大肠杆菌病及科学用药提供参考依据。

关键词: 鸡, 大肠杆菌, 分离鉴定, 耐药性分析, 致病性分析

Abstract: :A group of sick chicken suspected to be infected by Escherichia coliE. coli)were found in a large-scale chicken farm in Tianjin. In order to isolate the pathogenic bacteria of the chicken disease and analyze its pathogenicity, a comprehensive analysis was conducted including clinical diagnosis, collection of tissue samples, bacterial isolation and culture, identification of culture medium and biochemical methods, 16S rRNA detection, analysis of phylogenetic tree and homology, antimicrobial susceptibility tests, virulence gene detection, mice pathogenicity test and histopathological observation. The results showed that typical peritonitis, perihepatitis and pericarditis and other symptoms were found in clinical autopsy. The isolate was negative short bacillus by Gram staining and was consistent with the growth characteristics of E. coli via the culture medium and biochemical identification. PCR amplification with 16S rRNA specific primers, phylogenetic tree and homology analysis showed that the isolate was related to E. coli in the same branch, and the homology was more than 99.99%. The isolate was susceptible to florfenicol and moderately susceptible to tetracycline and doxycycline. E. coli virulence genes including fimC, hlyF, ompT, and iroN were amplified by PCR. Animal pathogenicity test showed that all mice inoculated with the isolate died within 16 h, and the bacteria were detected in the liver and blood of the infected mice. Histopathological observation showed that the liver, heart, lung, kidney, spleen and intestine of infected mice were damaged to varying degrees. The results showed that the isolate was E. coli, and the isolate had multiple antibiotic resistance and carried a variety of virulence genes, which had strong pathogenicity to animals. The results of this study provide reference for the prevention and control of E. coli and reasonal use of antibiotics in chicken farms.

Key words: chicken, Escherichia coli, isolation and identification, antimicrobial resistance, pathogenicity analysis

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