Bovine-associated Klebsiella pneumoniae is an important bacterial species linking animal health, microbial ecology, and One Health-oriented antimicrobial resistance research. In this study, we performed a global genomic analysis of 1291 publicly available bovine-associated K. pneumoniae genomes collected from 18 countries between 2005 and 2024 using data retrieved from NCBI. MLST, core-genome phylogenetic analysis, pangenome analysis, CARD, VFDB, and PlasmidFinder were used to characterize sequence types, genomic diversity, antimicrobial resistance-associated genes, virulence-associated genes, and plasmid replicons. A total of 256 sequence types were identified, among which ST107 was the most common. Core-genome phylogenetic analysis revealed multiple genomic lineages, while pangenome analysis identified 46,325 gene clusters, including 1967 core genes and 40,595 cloud genes, indicating an open pangenome structure and substantial accessory gene diversity. Virulence-associated genes were unevenly distributed, with yagZ/ecpA being the most frequently detected determinant. In total, 138 antimicrobial resistance-associated genes or potential resistance determinants were detected across 16 antimicrobial categories, including clinically important β-lactamase- and carbapenemase-associated genes. IncF-family plasmid replicons, particularly IncFIB(K)_1_Kpn3, were frequently detected, suggesting widespread plasmid replicon-associated genomic backgrounds; however, physical co-localization between resistance genes and specific plasmid backbones could not be confirmed. Overall, this study reveals the genetic diversity, resistance-associated gene reservoir potential, heterogeneity of virulence-associated genes, and plasmid replicon backgrounds of bovine-associated K. pneumoniae. Importantly, the genome-predicted AMR potential identified in this study should not be interpreted as confirmed phenotypic resistance without further experimental validation. These findings provide genomic insights for risk surveillance, candidate control-target screening, and microbiota-oriented intervention research.

Staphylococcus aureus is an important zoonotic pathogen that threatens public health, food safety, and livestock production. Bacteriophages are promising antibacterial agents for controlling antimicrobial-resistant S. aureus, but their biological properties and genomic safety require systematic evaluation. In this study, three S. aureus phages, vB_SauL_202501, vB_SauM_202502, and vB_SauL_202503, were isolated from sewage samples and characterized by morphological observation, biological assays, whole-genome sequencing, and phylogenetic analysis. Transmission electron microscopy showed that vB_SauL_202501 and vB_SauL_202503 exhibited siphovirus-like morphology, whereas vB_SauM_202502 displayed myovirus-like morphology. Among the three phages, vB_SauM_202502 showed a relatively broader lytic spectrum and stronger sustained lytic activity in the spot assay. The optimal multiplicities of infection were 0.1, 0.1, and 0.01, respectively, and vB_SauL_202503 showed the shortest latent period, approximately 30 min. All three phages retained detectable infectivity at pH 5–10 and 4–37 °C, while vB_SauM_202502 maintained relatively high residual titers after heat treatment and ultraviolet irradiation. Genome analysis revealed double-stranded DNA genomes of 43,180–44,630 bp with GC contents of approximately 33.5%. No typical antimicrobial resistance genes or definitive auxiliary metabolic genes were identified. However, genes associated with lysogenic regulation, recombination, or immune modulation were detected in some phages, indicating that their lifestyles and application safety require further validation. These findings enrich S. aureus phage resources and provide a basis for the comparative characterization and safety assessment of candidate phages.