Comparative Genomics Approaches to Understanding Virulence and Antimicrobial Resistance of Salmonella Typhimurium ST1539 Isolated from a Poultry Slaughterhouse in Korea

Abstract

Non-typhoidal Salmonella (NTS) is one of the most frequent causes of bacterial foodborne illnesses. Considering that the main reservoir of NTS is the intestinal tract of livestock, foods of animal origin are regarded as the main vehicles of Salmonella infection. In particular, poultry colonized with Salmonella Typhimurium (S. Typhimurium), a dominant serotype responsible for human infections, do not exhibit overt signs and symptoms, thereby posing a potential health risk to humans. In this study, comparative genomics approaches were applied to two S. Typhimurium strains, ST1539 and ST1120, isolated from a duck slaughterhouse and a pig farm, respectively, to characterize their virulence and antimicrobial resistance-associated genomic determinants. ST1539 containing a chromosome (4,905,039 bp; 4,403 CDSs) and a plasmid (93,876 bp; 96 CDSs) was phylogenetically distinct from other S. Typhimurium strains such as ST1120 and LT2. Compared to the ST1120 genome (previously deposited in GenBank; CP021909.1 and CP021910.1), ST1539 possesses more virulence determinants, including ST64B prophage, plasmid spv operon encoding virulence factors, genes encoding SseJ effector, Rck invasin, and biofilm-forming factors (bcf operon and pefAB). In accordance with the in silico prediction, ST1539 exhibited higher cytotoxicity against epithelial cells, better survival inside macrophage cells, and faster mice-killing activity than ST1120. However, ST1539 showed less resistance against antibiotics than ST1120, which may be attributed to the multiple resistanceassociated genes in the ST1120 chromosome. The accumulation of comparative genomics data on S. Typhimurium isolates from livestock would enrich our understanding of strategies Salmonella employs to adapt to diverse host animals.

Comparative genomics analysis of Streptococcus iniae isolated from Trachinotus ovatus: novel insight into antimicrobial resistance and virulence differentiation

“…Fanelli et al identified a large number of antibiotic, heavy metals and virulence determinants by reporting the whole genome sequencing and genomic characterization of two Arcobacter butzleri strains isolated from shellfish [ 14 ]. Similarly, the virulence and antimicrobial resistance-associated genomic determinants of two Salmonella Typhimurium strains were reported through comparative genomics approaches [ 15 ]. Although some complete genome sequences of S.iniae isolated have been sequenced, to our knowledge, there have been no reports on the comparative genomics analysis for understanding the genetic basis of pathogenicity and multidrug resistance.…”

Genome-Wide Searching Single Nucleotide-Polymorphisms (SNPs) and SNPs-Targeting a Multiplex Primer for Identification of Common Salmonella Serotypes

“…The prevalent Salmonella is widely found in diverse sources, including environment, animal-originated foods, water, and animals, specifically wild animals, including wild birds [ 11 , 12 , 13 ], wild pigs [ 14 ], poultry and their eggs [ 15 ], and cattle [ 16 ]. It can be disseminated to humans via ingestion of contaminated food of animal origins, including pork, chicken, eggs, beef, and milk [ 17 , 18 , 19 ].…”