Genomic insights into Metapseudomonas otitidis PA-NS83: The first clinical isolate from Thailand and its comparative genomic analysis.

Metapseudomonas otitidis was first isolated from human middle ear fluid and has since been detected in both environmental and clinical samples, emerging as an opportunistic pathogen linked to chronic otitis media and other infections. This study reports the first clinical isolate of M. otitidis from Thailand, PA-NS83, and presents a comprehensive genomic characterization. Whole-genome sequencing and comparative analysis with 37 publicly available M. otitidis genomes revealed a diverse antimicrobial resistance (AMR) profile, with PA-NS83 carrying AMR genes commonly found in environmental isolates. Virulence gene analysis identified key determinants associated with biofilm formation, motility, secretion systems, and iron acquisition, highlighting its potential pathogenicity. Pan-genome analysis demonstrated substantial genomic diversity, with PA-NS83 clustering closely with M. otitidis CSMC7, an environmental isolate from polystyrene waste. However, PA-NS83 harbored 419 unique genes, including virulence-associated genes and a CRISPR-Cas system, suggesting adaptation to clinical settings. These findings underscore the genetic plasticity of M. otitidis and its potential role in human infections. Continued genomic surveillance and functional studies are essential to further assess its clinical significance and antimicrobial resistance mechanisms.