摘要
从湖南某猪场断奶后腹泻仔猪粪便中分离到2株疑似大肠杆菌,命名为H株和J株。为鉴定其致病性大肠杆菌类型,本研究将H株和J株分别接种伊红美蓝琼脂平板鉴别培养基和大肠杆菌IMViC生化鉴定试剂,并采取分子鉴定技术对其进行微生物种属鉴定;同时采取PCR扩增技术分析其携带大肠杆菌的肠毒素、黏附素以及α-溶血素、志贺样毒素2型变异体(Stx2e)、耶尔森氏菌毒力岛(HPI)等毒力因子情况。为了解H株和J株的耐药性,本研究使用微量肉汤稀释法对其进行最低抑菌浓度(MIC)测定,并参照CLSI M100-S33抗微生物药物敏感性试验执行标准进行耐药性分析。结果显示,H株、J株的伊红美蓝琼脂平板培养特性、大肠杆菌IMViC生化鉴定试验结果、分子鉴定结果均符合大肠杆菌典型特征;毒力因子分析结果为:H株为LT^(+)+STa^(+)+STb^(+)+EAST-1^(+)+F18^(+)+Stx2e^(+)+α-溶血素+,J株为STa^(+)+STb^(+)+HPI^(+);耐药性分析结果为:H、J株均对氨苄西林、四环素、氟苯尼考、磺胺异噁唑、复方新诺明耐药和对阿莫西林/克拉维酸、庆大霉素、头孢他啶、恩诺沙星、美罗培南敏感;不同的是H株对大观霉素、粘杆菌素耐药和头孢噻呋中介,而J株对大观霉素、头孢噻呋敏感和粘杆菌素中介。本研究上述结果表明H株、J株均为产肠毒素型大肠杆菌(ETEC),但携带的毒力因子各不相同,且均存在多重耐药,与浙江、河北、江西、福建和广西的猪源ETEC耐药情况的比较分析表明养殖环节大肠杆菌耐药性具有复杂性。本研究既为大肠杆菌毒力因子研究和猪场防控大肠杆菌感染引起的仔猪断奶后腹泻病(PWD)提供了参考,也为如何减少兽用抗菌药的使用提供了新思路:兽用抗菌药+疫苗+益生菌+噬菌体+益生元的综合防控手段。
Two strains of suspected Escherichia coli were isolated from the feces of post-weaning diarrheic piglets in a pig farm in Hunan Province,and were named strain H and strain J.To identify their pathogenic Escherichia coli types,in this study,strain H and strain J were respectively inoculated on eosin methylene blue agar plate differential medium and Escherichia coli IMViC biochemical identification reagents,and molecular identification technology was used for microbial species identification.Meanwhile,PCR amplification technology was employed to analyze their carrying status of virulence factors of Escherichia coli,such as enterotoxins,adhesins,as well asα-hemolysin,Shiga-like toxin type 2 variant(Stx2e),and Yersinia high-pathogenicity island(HPI).To understand the drug resistance of strain H and strain J,the minimum inhibitory concentration(MIC)was determined using the broth microdilution method,and drug resistance analysis was performed with reference to the CLSI M100-S33 standard for antimicrobial susceptibility testing.The results showed that the cultural characteristics on eosin methylene blue agar plates,the results of Escherichia coli IMViC biochemical identification test,and the molecular identification results of strain H and strain J all conformed to the typical characteristics of Escherichia coli.The results of virulence factor analysis are as follows:Strain H is LT^(+)+STa^(+)+STb^(+)+EAST-1^(+)+F18^(+)+Stx2e^(+)+α-hemolysin+,and Strain J is STa^(+)+STb^(+)+HPI^(+).The results of the drug resistance analysis are as follows:Both strains H and J are resistant to ampicillin,tetracycline,florfenicol,sulfisoxazole,and cotrimoxazole,and sensitive to amoxicillin/clavulanic acid,gentamicin,ceftazidime,enrofloxacin,and meropenem.The difference is that strain H is resistant to spectinomycin and colistin and intermediately resistant to ceftiofur,while strain J is sensitive to spectinomycin and ceftiofur and intermediately resistant to colistin.The above results of this study indicate that both strain H and strain J are enterotoxigenic Escherichia coli(ETEC),but they carry different virulence factors and both exhibit multidrug resistance.A comparative analysis with the drug resistance of porcine-derived ETEC in Zhejiang,Hebei,Jiangxi,Fujian,and Guangxi shows the complexity of Escherichia coli resistance in the breeding process.This study not only provides a reference for research on Escherichia coli virulence factors and prevention and control of post-weaning diarrhea(PWD)in piglets caused by Escherichia coli infection in pig farms,but also offers new ideas for reducing the use of veterinary antibiotics:a comprehensive prevention and control approach combining veterinary antibiotics+vaccines+probiotics+bacteriophages+prebiotics.
作者
马欣
刘博
魏津
张效斌
朱良全
李霆
王琦
王雨雨
姚文生
MA Xin;LIU Bo;WEI Jin;ZHANG Xiao-bin;ZHU Liang-quan;LI Ting;WANG Qi;WANG Yu-yu;YAO Wen-sheng(China Institute of Veterinary Drug Control,Key Laboratory of Animal Antimicrobial Resistance Surveillance,Ministry of Agriculture and Rural Affairs,P.R.China,Beijing 100081,China;Guangxi DBN Animal Husbandry and Food Co.,Ltd.,Guangzhou Branch,Guangzhou 510000,China)
出处
《中国兽药杂志》
2026年第2期42-53,共12页
Chinese Journal of Veterinary Drug
基金
国家重点研发计划(2022YFF0711002)。
关键词
猪源
产肠毒素型大肠杆菌
分离鉴定
毒力因子
耐药性
swine-derived
enterotoxigenic Escherichia coli
isolation and identification
virulence factors
drug resistance
