Unravelling the genomic landscape of Acinetobacter baumannii: deep dive into virulence factors, resistance elements, and evolutionary adaptations.

Abstract

The increasing prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Acinetobacter baumannii presents a major global health threat, particularly in hospital settings. Understanding the genomic landscape of A. baumannii is essential to elucidate its virulence mechanisms, resistance profiles, and evolutionary adaptations, which are critical for developing novel therapeutic strategies. This study aims to comprehensively analyze the pan-genome, antimicrobial resistance (AMR) genes, virulence factors, and clonal relationships of A. baumannii, with the goal of uncovering insights into its pathogenicity and genomic evolution. A total of 27,884 A. baumannii genomes were retrieved from GenBank for analysis. Genome annotation was carried out using Prokka, and pan-genome analysis was performed with Roary. AMR genes and virulence factors were identified through AMRFinderPlus and the Virulence Factor Database via Abricate. Temporal trends in AMR and virulence were analyzed statistically to assess changes over time. The study found that A. baumannii possesses a stable core genome and a highly diverse accessory genome, suggesting an open pan-genome structure. Temporal analysis revealed a significant increase in AMR genes, including bla_OXA-23, bla_NDM-1, and pmrCAB. Virulence genes were widely distributed across strains, with the sequence types (ST) like ST2^Pas clone exhibiting global dissemination, highlighting the strain's potential for widespread pathogenicity. This comprehensive genomic analysis of A. baumannii reveals its significant genomic diversity and adaptability, underscoring the critical role of both core and accessory genomes in shaping its pathogenicity and resistance mechanisms. The increasing prevalence of key AMR genes, alongside the widespread dissemination of virulent clones, highlights the urgent need for enhanced surveillance and novel therapeutic strategies to control the spread of this global pathogen. Future research should focus on the functional characterization of resistance and virulence factors to better understand their roles in pathogenicity and to facilitate the development of targeted interventions against A. baumannii.