Genomic epidemiology and pathogenic potential of Elizabethkingia meningoseptica: a comparative genomic analysis with experimental characterization of a clinical isolate

To characterize the population structure, antimicrobial resistance landscape, and virulence potential of Elizabethkingia meningoseptica based on publicly available genomes and a clinical isolate E0725. We analyzed 96 public genomes together with E0725 for core-genome single-nucleotide polymorphisms (SNPs), average nucleotide identity (ANI), antimicrobial resistance genes, and virulence genes. E0725 was further evaluated by antimicrobial susceptibility testing, biofilm formation, Galleria mellonella infection, serum resistance, bile salt tolerance, and oxidative-stress assays. The 97 strains belonged to multiple genetic lineages with weak geographic clustering and few near-clonal clusters. BlaB- , GOB- , CME- , and RASA-like β-lactamases and conserved core virulence genes were widely present, whereas variation mainly involved accessory resistance genes and cell-surface structure genes. E0725 was multidrug-resistant and showed strong biofilm formation, serum resistance, bile salt tolerance, and lethality in G. mellonella , but was sensitive to hydrogen peroxide. E. meningoseptica is genetically diverse, with a conserved intrinsic resistance backbone and variable accessory genomic features. The clinical isolate E0725 exhibited strain-specific phenotypic traits associated with biofilm formation, serum tolerance, and host-associated adaptation. Accurate identification, isolate-specific susceptibility testing, genomic surveillance, and management of hospital water systems should be prioritized for infection control. Not applicable.