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

Abstract

The worldwide spread of carbapenem-resistant <i>Acinetobacter baumannii</i> (CRAB) has become a healthcare challenge for some decades. To understand its molecular epidemiology in Southern Thailand, we conducted whole-genome sequencing (WGS) of 221 CRAB clinical isolates. A comprehensive bioinformatics analysis was performed using several tools to assemble, annotate, and identify sequence types (STs), antimicrobial resistance (AMR) genes, mobile genetic elements (MGEs), and virulence genes. ST2 was the most prevalent ST in the CRAB isolates. For the detection of AMR genes, almost all CRAB isolates carried the <i>bla</i> _OXA-23 gene, while certain isolates harbored the <i>bla</i> _NDM-1 or <i>bla</i> _IMP-14 genes. Also, various AMR genes were observed in these CRAB isolates, particularly aminoglycoside resistance genes (e.g., <i>armA</i>, <i>aph(6)-Id</i>, and <i>aph(3″)-Ib</i>), fosfomycin resistance gene (<i>abaF</i>), and tetracycline resistance genes (<i>tet</i>(B) and <i>tet</i>(39)). For plasmid replicon typing, RepAci1 and RepAci7 were the predominant replicons found in the CRAB isolates. Many genes encoding for virulence factors such as the <i>ompA</i>, <i>adeF</i>, <i>pgaA</i>, <i>lpxA</i>, and <i>bfmR</i> genes were also identified in all CRAB isolates. In conclusion, most CRAB isolates contained a mixture of AMR genes, MGEs, and virulence genes. This study provides significant information about the genetic determinants of CRAB clinical isolates that could assist the development of strategies for improved control and treatment of these infections.