China Animal Husbandry and Veterinary Medicine ›› 2022, Vol. 49 ›› Issue (6): 2385-2396.doi: 10.16431/j.cnki.1671-7236.2022.06.038

• Basic Veterinary Medicine • Previous Articles     Next Articles

Isolation, Identification and Analysis of Pathogenicity and Drug Resistance of Salmonella from Sheep

WANG Simin1,2, YANG Jiangfeng2, ZHAO Xiaokun2, ZHANG Lei2, GUO Jingjing1, LAN Jinping2, YU Xiaojie2, WANG Jing2   

  1. 1. Agricultural and Rural Bureau of Xuanhua District, Zhangjiakou City, Zhangjiakou 075100, China;
    2. Hebei Mutton Sheep Industry Technology Inovation Strategic Alliance, College of Animal Science and Technology, Hebei North University, Zhangjiakou 075000, China
  • Received:2021-11-02 Online:2022-06-05 Published:2022-05-27

Abstract: 【Objective】 The study was aimed to isolate and detect the serotype, virulence gene, drug resistance and drug resistance gene of Salmonella from sheep in Zhangjiakou, and analyze the correlation and difference between phenotype and gene.【Method】 The collected samples were inoculated and purified with selective medium.Suspected single colonies were selected for Gram staining, microscopic examination and biochemical identification.PCR identification and serotype identification were carried out according to the nucleotide sequence of Salmonella specific gene invA.SPF Kunming mice were used to test the pathogenicity of the isolates and determine the median lethal dose.Then the virulence island genes hilA, avrA, sseL, ssaQ, mgtC, siiD and sopB, enterotoxin gene stn, plasmid virulence gene spvR were amplified.Kirby-Bauer disk diffusion method was used for drug sensitivity test to amplify drug resistance β-lactamase genes including blaTEM, blaCMY, blaOXA, fluoroquinolone genes qnrS, oqxA, oqxB, sulfonamide resistance genes sul1, sul2, sul3, tetracycline resistance gene tetB and aminoglycoside resistance gene aadA1.According to the PCR results, the target virulence gene and drug resistance gene were sent to sequence, and BLAST comparison analysis was carried out with the corresponding reference gene in NCBI.【Result】 4 strains of Salmonella from sheep were isolated and identified as Salmonella Typhimurium.The isolates were pathogenic to mice, and the median lethal doses of 4 isolates were between 5.67×107 and 6.45×107 CFU.The isolated strains could detect virulence island genes hilA, avrA, sseL, ssaQ, mgtC, siiD, sopB, enterotoxin gene stn and plasmid virulence gene spvR, and the positive detection rates were all >50%.The isolates had strong resistance to compound sulfamethoxazole, rifampicin, lincomycin, penicillin and ampicillin, and were sensitive to gentamicin and ciprofloxacin.Drug resistance was detected in the isolates, β-lactam gene blaTEM, fluoroquinolone gene qnrS and sulfonamide resistance genes sul1 and sul2 were positive.【Conclusion】 The virulence phenotype of Salmonella isolated from sheep was related to the virulence genes carried by chromosomes and plasmids.The isolated strains carried β-lactam and sulfonamide resistance genes, which were consistent with the drug resistance phenotype.Gentamicin and ciprofloxacin could be used as the first choice in clinic.

Key words: Salmonella from sheep; pathogenicity; virulence gene; drug resistance; drug-resistance gene

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