Whole genome sequence-based characterization of foodborne Staphylococcus aureus isolated from pork in 2018 and 2023.

This study characterizes the genomic epidemiology of 111 Staphylococcus aureus isolates collected from retail meat in Beijing and Copenhagen during 2018 and 2023 using whole-genome sequencing. Our analysis identified concerning antimicrobial resistance patterns, with methicillin-resistant S. aureus (MRSA) prevalence rising from 19.51% to 24.13% over the study period. The livestock-associated CC398 lineage (27.03% of isolates) demonstrated strong correlations with tetracycline resistance (tetM) and persisted as the dominant clone in Beijing, increasing from 33.33% to 40.91% prevalence. In contrast, we observed the rapid emergence of community-associated CC8 strains in Denmark, reaching 71.43% prevalence by 202327. Virulence profiling revealed MSSA strains frequently carried enterotoxin genes (seg/sei in 55.8% of isolates), while mobile genetic elements like SCCmec IV in ST59-t437 contributed significantly to pathogenicity. Phylogenetic analysis delineated five major clades and highlighted the expansion of multidrug-resistant CC398 strains in Beijing. These findings demonstrate the dynamic evolution of S. aureus at the human-animal interface and emphasize the urgent need for integrated One Health surveillance systems to track resistance gene dissemination. Future research should prioritize investigating zoonotic transmission pathways and the role of horizontal gene transfer in driving the convergence of virulence and resistance traits in foodborne pathogens.