Zhongguo shipin weisheng zazhi (Jul 2024)

Phenotypic and genomic characterization of 145 Salmonella strains from foodborne patients and raw poultry in Shaoxing City in 2020

  • ZHANG Qinchao,
  • ZHOU Liangkang,
  • CHEN Jiming,
  • TANG Shijie,
  • HE Qinfen

DOI
https://doi.org/10.13590/j.cjfh.2024.07.002
Journal volume & issue
Vol. 36, no. 7
pp. 774 – 781

Abstract

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ObjectiveTo monitor the molecular epidemiology and antimicrobial resistance pattern of Salmonella isolates recovered from the clinical and the food sources in Shaoxing City, the genomic characterization of some clinical strains were analyzed.MethodsSlide agglutination method was used to determine the serovars. PFGE method was applied to study molecular classification. Broth microdilution method was performed to carry out drug resistance testing. Whole genome data were sequenced. Whole genome single nucleotide polymorphism (wgSNP) classification was performed by BioNumerics V7.6 software. The sequence types (ST), drug resistant genes and virulence genes were predicted with Pubmlst, ResFinder 4.1 and VFDB software, respectively.ResultsTwenty-four serotypes, 109 different PFGE fingerprints, 80 resistant patterns were detected in 135 clinical and the 10 food isolates of Salmonella. The predominant serovars were Salmonella typhimurium, Salmonella enteritidis and Salmonella london. The main serotypes in food were Salmonella london and Salmonella paratyphi B. Salmonella had high resistance to ampicillin, tetracycline and streptomycin. The multiple drug resistance rate reached 73.79% (107/145). The main drug resistance in food were ampicillin, cefazolin, tetracycline and nalidixic acid. A total of 11 diverse ST types were identified from the 30 clinical strains. Phylogenetic wgSNP comparisons demonstrated that four Salmonella enteritidis from ST11 types were genetically similar and clustered together. A total of 31 different antimicrobial resistance genes among these isolates were identified. The most common antimicrobial resistance genes were the aminoglycosides resistance gene aac(6')-Iaa (100%, 30/30), the β-lactams resistance gene blaTEM-1B (70%, 21/30) and so on. A total of 224 virulence genes were also identified, and 107 of these existed among all isolates.ConclusionSalmonella in Shaoxing had a variety of serotypes and PFGE fingerprints, a complex resistant patterns, a high proportion of multiple drug resistance. The findings showed that selected raw poultry was not a direct source of local Salmonella infection. Part of the clinical strains had a high carrying rate of antimicrobial resistance genes and virulence genes.

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