Whole-genome Study of Carbapenem-resistant Acinetobacter baumannii Virulence and Resistance

Background and Aim: Carbapenem-resistant Acinetobacter baumannii (CRAb) has ability to develop and acquire resistance makes it one of the most critical nosocomial pathogens globally. Whole genome sequemcing (WGS) technology was employed to map genes associated with antimicrobial resistance (AMR),virulene factors and to identify multilocus sequence types (MLST). In order to understand the resistance mechanism for A. baumannii species, this study set out to establish the genetic makeup of the species. Materials and Methods: Whole-genome sequencing (WGS) of A.b۴, A.b۴۹ and A.b۷۵ was performed using Illumina MiSeq and the genomes were assembled with SPAdes. ARG-ANNOT, CARD-RGI, VFDB, PHAST, PlasmidFinder were used to analyse all genomes. Results: Genome analysis revealed that Ab۴ belongs to ST۹۴۴, represented singletons that could not be attributed to any, A.b۴۹ belongs to ST۱۱۰۴, represented unique ST.While A.b۷۵ belongs to ST۱۹۵ which represented known international clones of high risk .Molecular characterisation showed the presence ۲۳ antibiotic resistance genes in all straines of A. baumannii. ۱۲ of them are shared by all ۳ strains and ۱۱ are common between A. baumannii ۴(ST/۹۴۴), ۴۹ (ST/۱۱۰۴) and ۷۵(ST/۱۹۵). The common drug-resistance genes shared by all ۳ strains include bla OXA-۷۲ (resistance to carbapenems), ade genes, RND (adeFJK, adeLN & adeR), and SMR   (abeS) encoding for efflux pumps. Conclusion: We present WGS analysis of three A. baumannii strains belonging to three different STs. The presence of strains harboring acquired AMR genes makes them more dangerous. Acquired resistance genes and chromosomal gene mutation are successful routes for disseminating AMR determinants among A. baumannii. Identification of chromosomal and plasmid-encoded AMR in the genome of A. baumannii may help understand the mechanism behind the genetic mobilization and spread of AMR genes.

کلیدواژه ها:

A. baumannii ، carbapenem-resistant ، WGS ، antibiotic resistance ، virulence traits ، Multi-Locus Sequence Typing (MLST) ، A. baumannii ، مقاوم به کارباپنم ، WGS ، مقاومت آنتی بیوتیکی ، صفات حدت ، تایپ توالی چند جایگاهی (MLST)