Molecular characterization of extremely-drug resistant Acinetobacter baumannii from Brazil

Acinetobacter baumannii is an important nosocomial pathogen related to serious infections. Among them, carbapenem resistance rates can be as high as 80%. Most carbapenem-resistant clones have also acquired resistance determinants to other antimicrobial classes, such as aminoglycosides, fluoroquinolones, tetracyclines, tigecycline and, more recently, polymyxins, and are now classified as extremely drug-resistant (XDR) or pan-drug resistant (PDR). The majority of such isolates belongs to the worldwide disseminated International Clone 2 (IC2). However, the isolates presenting such phenotype in South America are not associated with IC2. In Brazil, the major carbapenemase-producing clones belong to clonal complexes (CCs) 15 and 79 - IC4 and IC5, respectively. A comprehensive study on the genetic basis of XDR phenotype in such important ICs are still missing. In this study, we explored the molecular determinants associated with an XDR phenotype among A. baumannii clinical isolates belonging to South America major clones.