Comparative Genomic and Phylogenetic Analysis of Salmonella enterica Isolated From Donkey

Salmonella is one of the most prevalent foodborne and zoonotic pathogens threatening global public health and food safety. Salmonella enterica subspecies enterica serovar Abortusequi (S. Abortusequi) is frequently reported as the etiological agent of equine abortion, septicemia, and polyarthritis. Currently, comprehensive studies on the virulence traits, evolutionary dynamics, and genomic diversity of donkey S. Abortusequi are limited. In this study, we assessed the genomic epidemiology, antibiotic resistance, and pathogenic traits of a ST251 S. Abortusequi strain (XJP1), isolated from donkey, using the core genome single nucleotide polymorphism (cgSNP) phylogenetic analysis, core genome multilocus sequence typing (cgMLST), comparative genomic analysis, the antimicrobial susceptibility tests, and virulence assays. Our cgSNP and cgMLST analyses indicate that XJP1 is closely related to Salmonella enterica subspecies enterica strains isolated from humans, equines, donkeys, poultry, and associated with multiple serovars. Additionally, XJP1 exhibited a multidrug-resistant profile, showing resistance to seven antibiotics. In a mouse infection model, XJP1 showed significantly higher lethality compared to the XJS1 strain. Notably, XJP1 harbored a plasmid containing an IncFIB/IncFII incompatibility group replicon and carrying the spvBC operon, as well as the rck, TTSS, pefABCD, fdeC virulence genes, and gadX acid resistance transcriptional activators gene. Our findings suggest that this plasmid may be a critical virulence determinant in XJP1. In conclusion, our data on the epidemiology and pathogenicity of ST251 S. Abortusequi provide valuable insights into the genetic, virulence, and transmission dynamics of donkey Salmonella enterica, highlighting the need for attention to food safety measures and public health surveillance.