China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (4): 1663-1674.doi: 10.16431/j.cnki.1671-7236.2023.04.037

• Basic Veterinary Medicine • Previous Articles     Next Articles

Isolation,Identification and Drug Resistance and Pathogenicity Analysis of Salmonella Enteritidis from Avian

WANG Lucai, SALANG Wenzhu, ZHANG Huanrong   

  1. College of Animal & Veterinary Sciences, Southwest Minzu University, Chengdu 610041, China
  • Published:2023-04-06

Abstract: 【Objective】 In order to reasonably prevent and control Salmonella Enteritidis (S.Enteritidis) infection,this experiment was conducted on the infection of S.Enteritidis from avian in four regions of Sichuan.【Method】 Bacterial isolation and identification was carried out by bacterial isolation and culture,biochemical test and molecular method.The sensitivity of isolated bacteria to 14 antibacterial drugs was further detected by K-B method,and drug resistance genes,virulence genes and pathogenicity of isolated bacteria were studied.【Result】 The results of bacterial isolation and culture showed that the isolated bacteria conformed to the culture characteristics of Salmonella,the microscopic examination was Gram-negative short bacilli,and the biochemical identification results were consistent with the biochemical characteristics of Salmonella.The PCR amplification results of Salmonella specific virulence target gene invA and S. Enteritidis specific virulence target gene sdfI showed that the target bands of 571 and 304 bp were obtained,which were consistent with the expected size.It was confirmed that 10 strains of S.Enteritidis were isolated,with a total isolation rate of 2.8% (10/361).The results of drug sensitivity test showed that the isolated bacteria had a high resistance rate to aminoglycosides,sulfonamides and peptides.Among aminoglycosides,the drug resistance rates to gentamicin and streptomycin were 50% (5/10) and 70% (7/10), respectively.Among sulfonamides,the drug resistance rates to compound sulfamethoxazole and sulfamethoxazole were 40% (4/10) and 100% (10/10) respectively.Among polypeptide drugs,the resistance rate to polymyxin B was 90% (9/10).The isolated bacteria were sensitive to quinolones,and moderately sensitive to cephalosporins β-lactamides and tetracyclines.Multiple drug resistance was common in isolated bacteria.Tetracycline resistance genes tetB (40.0%) and tetM (90%),aminoglycoside resistance genes aadA1 (80%) and aph(3')-Ⅱa (90%),β-lactam resistance gene blaTEM-1 (100%),sulfonamide resistance gene sul3 (100.0%) were detected in 14 drug resistance genes.Among the six virulence related genes,the detection rates of ssaQ (SPI-2),mgtC (SPI-3),spi4D (SPI-4),pipA (SPI-5),invA (SPI-1) and spvB were 60%,80%,70%,60%,100% and 80%,respectively.The results of the pathogenicity test showed that the mice died after 24 h of intragastric administration of isolated bacterial solution.Blood stasis,hemorrhage,cell degeneration,etc.were observed in the organs and pathological sections,and the villi in the intestinal segment were broken and shed.【Conclusion】 In this study,10 strains of S.Enteritidis from avian were successfully isolated,and the isolated bacteria had strong drug resistance and multiple drug resistance,and the detection rate of virulence genes of isolated bacteria was high and the pathogenicity was strong,which could provide reference for the prevention and control and clinical treatment of S.Enteritidis.

Key words: Salmonella Enteritidis; drug resistance; drug resistance gene; virulence gene; pathogenicity

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