Research Reveals Insights into Salmonella Typhimurium Antimicrobial Resistance and Virulence

Strategic Insights -

Recent research at Habib Bourguiba University Hospital in Sfax, Tunisia, has shed light on the antimicrobial resistance and virulence-associated genomic features of clinical Salmonella Typhimurium DT104 isolates. Among 88 S. Typhimurium isolates, 39.8% were definitive type DT104, and antimicrobial resistome analysis revealed clinically significant genes, including bla, bla, aadA2, sul1, sul2, tet(G), floR, dfrA5, and biocide resistance gene qacED1.

Key Takeaways:

  • Salmonella Typhimurium DT104 is a significant foodborne pathogen causing gastroenteritis in humans and animals, with high levels of antimicrobial resistance.
  • Whole-genome sequencing of 88 S. Typhimurium isolates revealed a high prevalence of clinically significant genes associated with antimicrobial resistance.
  • The most commonly detected prophages were Gifsy_1 and Gifsy_2, present in approximately 96.6% and 95.5% of isolates, respectively.
  • Virulence gene screening suggested that DT104 is not more pathogenic than non-DT104 isolates, and the presence of virulence plasmid genes was identified in approximately 95% of isolates.
  • Ten Salmonella pathogenicity islands (SPIs) encoding virulence factors were detected in all isolates except SPI-14 and CS54_island.
  • SNP analysis revealed clade-specific missense mutations within plasmid virulence, SPI-1, SPI-2, and fimbriae genes.
  • Continuous genomic surveillance is crucial for preserving human health.

Statistics:

  • 88 S. Typhimurium isolates were analyzed, with 39.8% being definitive type DT104.
  • 91% of DT104 strains and 34% of non-DT104 strains had b-lactam resistance associated with bla and bla genes, respectively.
  • 10 intact prophages were detected, with Gifsy_1 (96.6%) and Gifsy_2 (95.5%) being the most prevalent.
  • 95% of isolates had virulence plasmid genes.
  • 10 SPIs encoding virulence factors were detected in all isolates except SPI-14 and CS54_island.

Sources:

  • "Genome-based assessment of antimicrobial resistance, virulence-associated genes, and prophage diversity across clinical Salmonella Typhimurium isolates in the south of Tunisia." Microbial Pathogenesis, 2025;206:107850.