Pan-Resistome Insights into the Multidrug Resistance of Acinetobacter baumannii

Abstract

Acinetobacter baumannii is an important Gram-negative opportunistic pathogen that is responsible for many nosocomial infections. This etiologic agent has acquired, over the years, multiple mechanisms of resistance to a wide range of antimicrobials and the ability to survive in different environments. In this context, our study aims to elucidate the resistome from the A. baumannii strains based on phylogenetic, phylogenomic, and comparative genomics analyses. In silico analysis of the complete genomes of A. baumannii strains was carried out to identify genes involved in the resistance mechanisms and the phylogenetic relationships and grouping of the strains based on the sequence type. The presence of genomic islands containing most of the resistance gene repertoire indicated high genomic plasticity, which probably enabled the acquisition of resistance genes and the formation of a robust resistome. A. baumannii displayed an open pan-genome and revealed a still constant genetic permutation among their strains. Furthermore, the resistance genes suggest a specific profile within the species throughout its evolutionary history. Moreover, the current study performed screening and characterization of the main genes present in the resistome, which can be used in applied research to develop new therapeutic methods to control this important bacterial pathogen.

Whole-genome analysis of carbapenem-resistant Acinetobacter baumannii from clinical isolates in Southern Thailand

“…Based on our analysis, the pan-genome graph could be possibly considered as an open pan-genome since our dataset contained only 221 isolates. However, in the analysis of a larger dataset of A. baumannii isolates, the result also exhibited that exponential pan-genome growth was observed when increasing a great number of pan-genome [103] , [104] , [105] , [106] . Furthermore, the high proportion of accessory genes demonstrated a high genomic diversity among these isolates.…”

Genomic Characterization of Mobile Genetic Elements Associated With Carbapenem Resistance of Acinetobacter baumannii From India

“…The A. baumannii isolates in this study belonged to diverse sequence types (STs) representing four International clones, ICs (IC1/CC1, IC2/CC2, IC7/CC25, and IC8/CC10), one clonal complex, i.e., CC862, and one singleton ( Table 2 ). Although genes that confer resistance to different antimicrobials were identified across all clonal lineages, the majority of the genes that encode for aminoglycoside modifying enzymes, RMTases, macrolide resistance, sulfonamide resistance, chloramphenicol, and rifampicin resistance were confined to isolates belonging to IC2 ( Rodrigues et al, 2021 ; Hernández-González et al, 2022 ).…”

Genomic Diversity of Bacteriophages Infecting the Genus Acinetobacter

“…Although strains of A. baumannii show limited diversity among core genes, the genome is both plastic and dynamic, which is shown by significant variance in accessory gene content. A significant factor in the accessory genome variance is the acquisition of a wide variety of mobile genetic elements as well as hotspots of recombination, which has contributed to the evolution of extensive and pan-drug resistant phenotypes [9]. Notably, comparative analysis of isolates from international clonal lineage I has shown hotspots of recombination associated with capsular polysaccharide, lipooligosaccharide, and outer membrane proteins-surface structures which are commonly targeted by phages for adsorption [10,11].…”