[背景]猪只消化道疾病是养猪业上一大重要疾病,给养猪业带来一定的经济损失.大肠杆菌是引起猪腹泻的一种常见病原菌,可以引起不同日龄的猪腹泻,但主要以幼龄猪为主.[目的]旨在分离鉴定引起四川省眉山市一规模化养猪场病猪大规模腹泻的病原菌.[方法]采用常规细菌分离方法结合16S rRNA基因序列的分析方法从发病猪肝脏、胃以及污染的饲料分离鉴定细菌,并对分离株进行小鼠致病性试验、16S rRNA基因遗传进化树分析、毒力基因的检测、药物敏感试验.[结果]从腹泻猪肝脏中分离到一株致病性大肠杆菌,胃中分离到一株蜡样芽胞杆菌,并且追溯到传染源是该猪场饲料.通过检测这两株菌相应的毒力基因发现大肠杆菌不属于肠外致病性型,蜡样芽胞杆菌检测到了nheA、nheB、nheC、bceT、entFM 5种毒力基因;药敏试验表明常规的氨基糖苷类和头孢类抗生素对大肠杆菌抑菌效果较好,红霉素、氟苯尼考、头孢氨苄、头孢哌酮对蜡样芽胞杆菌抑菌效果较好,而蜡样芽胞杆菌对青霉素、阿莫西林等常规药物不敏感.[结论]饲料存在大肠杆菌和蜡样芽胞杆菌的混合污染.%[Background] Pig digestive tract disease is one of the most important diseases in the pig industry and brings certain economic losses to the swine industry. Escherichia coli is a common pathogen causing diarrhea of pigs at different ages, but mainly in young pigs. [Objective] The purpose of this study was to isolate and identify pathogens causing large-scale diarrhea in pigs on a large-scale pig farm in Meishan City, Sichuan Province. [Methods] Bacteria were isolated and identified from the infected pig liver, stomach and contaminated feed using conventional bacterial isolation methods combined with 16S rRNA gene sequence analysis. The isolates were tested for pathogenicity in mice, 16S rRNA gene phylogenetic analysis, virulence genes, and drug sensitivity testing. [Results] One pathogenic Escherichia coli was isolated from the liver of diarrhea pigs, one strain of Bacillus cereus was isolated from the stomach, and the source of infection was traced back to the feed on the farm. By detecting the corresponding virulence genes of these two strains, it was found that Escherichia coli is not extra-intestinal pathogenic type. Bacillus cereus was detected to have five virulence genes: nheA, nheB, nheC, bceT, entFM; Aminoglycosides and cephalosporins have good antibacterial effects on Escherichia coli. Erythromycin, florfenicol, cephalexin, cefoperazone have good antibacterial effect on Bacillus cereus, but the bacteria were not sensitive to conventional antibiotics such as penicillin and amoxicillin. [Conclusion] Feed is contaminated by Escherichia coli and Bacillus cereus.
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