Phylogenomic analysis of aquatic and clinical OXA-23-positive Acinetobacter baumannii belonging to the international clone 5 (ST79) from Southeast Brazil.

Categorized as a critical priority pathogen by the World Health Organization (WHO), carbapenem-resistant Acinetobacter baumannii (CRAB) is a leading cause of healthcare-associated infections (HAIs) worldwide. Although the environmental spread of healthcare-acquired A. baumannii strains through hospital wastewater and urban sewage has been suggested, evidence from genomic studies is still lacking. In this study, as part of the Grand Challenges Explorations: New Approaches to Characterize the Global Burden of Antimicrobial Resistance Program, we present genomic data supporting the expansion of international clone IC5/ST79 (Pasteur) to an anthropogenically impacted urban river in Brazil. The environmental OXA-23-producing A. baumannii Ab120 strain conserved a broad resistome to clinically important antimicrobials and carried efflux pump genes associated with tolerance to disinfectants. On the other hand, a wide virulome associated with colonization, evasion of the immune system, as well as survival and persistence in distinct environments was predicted. Noteworthy, a comparative phylogenomic analysis of the environmental Ab120 strain provided evidence that indicates its nosocomial origin and genomic relationship with human-derived OXA-23-positive clinical strains isolated between 2010 and 2017 in Brazil. Our genomic findings suggest adaptation of OXA-23-producing CRAB ST79 beyond hospital settings into non-clinical environments, which is a critical issue deserving active surveillance, particularly in Pan-American countries with a currently endemic clinical status.