Klebsiella oxytoca has emerged as an important opportunistic pathogen in nosocomial infections, particularly during the COVID-19 pandemic, due to its capacity to acquire and disseminate resistance and virulence genes through horizontal gene transfer (HGT). This study presents a genome-based comparative analysis of K. oxytoca within the genus Klebsiella, aimed at exploring the evolutionary plausibility of outer membrane vesicle (OMV) associated processes in bacterial adaptation. Using publicly available reference genomes, we analyzed pangenome structure, phylogenetic relationships, and the distribution of mobile genetic elements, resistance determinants, virulence factors, and genes related to OMV biogenesis. Our results reveal a conserved set of envelope associated and stress responsive genes involved in vesiculogenic pathways, together with an extensive mobilome and resistome characteristic of the genus. Although these genomic features are consistent with conditions that may favor OMV production, they do not constitute direct evidence of functional OMV mediated horizontal gene transfer. Instead, our findings support a hypothesis generating evolutionary framework in which OMVs may act as a complementary mechanism to established gene transfer routes, including conjugation, integrative mobile elements, and bacteriophages. Overall, this study provides a genomic framework for future experimental and metagenomic investigations into the role of OMV-associated processes in antimicrobial resistance dissemination and should be interpreted as a recently identified evolutionary strategy inferred from genomic data, rather than a novel or experimentally validated mechanism.
Tamayo-Ordóñez et al. (Mon,) studied this question.