Unveiling the genomic and phenotypic landscape of Acinetobacter species from different environmental sources in Brazil.

This study aimed to investigate the diversity of Acinetobacter spp. isolated from aquatic environments along the Brazilian coast, with a focus on environmental reservoirs of clinically relevant resistance genes. Twenty-three Acinetobacter isolates were recovered from marine animals, floating plastic, and surface water samples collected in two contrasting Brazilian regions: the heavily polluted Guanabara Bay (Rio de Janeiro) and the pristine Fernando de Noronha Archipelago (Pernambuco). Seven species were identified, with A. venetianus (n = 13) and A. johnsonii (n = 4) being the most frequent. Two A. johnsonii isolates carried the metallo-β-lactamase gene blaNDM-1, along with resistance to fluoroquinolones and carbapenems. Resistance to polymyxins and aminoglycosides was also observed in A. haemolyticus, A. baumannii, and A. modestus. ApaI-PFGE dendrogram and phylogenetic analyses based on single nucleotide position (SNPs) revealed high genetic diversity, and global comparisons placed the environmental isolates in lineages distinct from those commonly associated with healthcare-associated infections. This study highlights the diversity of Acinetobacter spp. in aquatic environments and their potential role as reservoirs of clinically important resistance genes, including blaNDM-1. By uncovering resistance mechanisms in environmental Acinetobacter strains, this work reinforces the relevance of environmental surveillance for One Health initiatives, particularly in regions with significant anthropogenic impact.