One Health Genomic Perspective on Pseudescherichia vulneris: A Neglected Reservoir of Last-Resort Resistance Genes

Antimicrobial resistance (AMR) is a critical global threat, often driven by horizontal gene transfer mediated by mobile genetic elements (MGEs) such as plasmids, transposons, and integrons. Among Enterobacterales, IncHI2/IncHI2A plasmids are of particular concern, as they combine broad host range, conjugative potential, and mosaic architecture enriched with ARGs, biocide tolerance, and heavy-metal resistance. This study provides the first systematic comparative genomics of Pseudescherichia vulneris , an underrecognized yet genomically versatile species at the human–animal–environment interface. All 30 publicly available genomes were analyzed to reconstruct the pangenome, resistome, virulome, and associated MGEs. The pangenome was open, reflecting ongoing diversification and strong potential for horizontal gene acquisition. Resistomes were highly heterogeneous, ranging from minimal repertoires in most animal and environmental isolates to multidrug-resistance profiles in hospital-associated and occasional animal genomes. Clinically significant determinants, including bla _KPC−2 , bla _KPC−3 , bla _CTX−M−9 , and mcr-9 , were frequently linked to MGEs. bla _KPC alleles were mobilized by Tn 4401 -like elements, while mcr-9 occurred either within IncHI2/IncHI2A plasmids or integrated into chromosomal contexts, underscoring diverse mobilization routes. In contrast, the virulome was comparatively conserved, dominated by motility, chemotaxis, and siderophore systems, unlike pathogenic Enterobacterales that carry broad MGE-associated virulence factors. Co-occurrence analyses showed modular independence between resistance and virulence, with limited overlaps shaped by ecological origins, suggesting that resistome content may adapt to distinctive environments. Collectively, these findings establish P. vulneris as a reservoir and conduit of last-resort resistance genes, reinforcing its relevance for One Health surveillance and highlighting the urgent need for its systematic inclusion in global antimicrobial resistance monitoring frameworks.