Abstract
Chryseobacterium and Elizabethkingia species are opportunistic pathogens increasingly
associated with severe hospital-acquired infections and multidrug resistance. This study aimed to
investigate the clinical characteristics, antimicrobial resistance profiles, and genomic features of
these two genera, as well as to assess their presence in the hospital environment. A total of 25
Chryseobacterium and 37 Elizabethkingia clinical isolates were collected from infected patients,
along with 132 environmental samples from Maharaj Nakorn Chiang Mai Hospital, Thailand.
Antimicrobial susceptibility testing was performed, and whole-genome sequencing (WGS) combined
with hybrid assembly was used for comprehensive genomic analysis. Most infected patients were
elderly, had severe underlying comorbidities, and frequently presented with concomitant
infections. Both genera exhibited high levels of multidrug resistance; however, Elizabethkingia
isolates remained relatively susceptible to levofloxacin and trimethoprim/sulfamethoxazole. No
Chryseobacterium or Elizabethkingia species were detected in environmental samples. Genomic
analysis revealed that Chryseobacterium genomes ranged from 4.11 to 5.25 Mb, whereas
Elizabethkingia genomes ranged from 3.87 to 4.27 Mb. Whole-genome sequencing enabled highresolution species-level identification and revealed multiple antimicrobial resistance genes located
on the chromosome. Notably, Chryseobacterium indologenes harbored clustered resistance genes
within genomic islands, providing evidence of horizontal gene transfer. In addition, both genera
carried multiple virulence-associated genes. Single nucleotide polymorphism (SNP) analysis
suggested the possibility of localized transmission within a medical ward. In conclusion,
Chryseobacterium and Elizabethkingia isolates from Maharaj Nakorn Chiang Mai Hospital
demonstrated high-level multidrug resistance and significant pathogenic potential. Genomic
analyses elucidated complex resistance mechanisms and highlighted the value of genomic
surveillance in supporting infection control strategies and promoting appropriate antimicrobial
stewardship in hospital settings.
