Antimicrobial resistance (AMR) extends beyond the clinical environment and involves ecosystems impacted by sewage and heavy metals, which promote the co-selection of resistant microorganisms. The collapse of the Brumadinho dam (Minas Gerais, Brazil) exemplifies how environmental disasters intensify this dynamic. The lack of proper sanitation worsens the situation by increasing the release of antimicrobial resistance genes (ARGs) into water bodies. This study investigates ARGs, resistant bacteria, and metals in affected and unaffected areas to better understand the mechanisms driving AMR dissemination.

Twenty-three environmental samples from the Paraopeba River basin were analyzed, including areas affected and unaffected by the Brumadinho dam collapse. Samples included raw sewage, influent and effluent from wastewater treatment plants (WWTPs), and river segments. DNA was extracted and the genes blaKPC, blaNDM, blaOXA-48-like, and blaVIM were quantified by qPCR (SYBR Green). Resistant bacteria were isolated in selective media and identified using MALDI-ToF. Metal concentrations were determined by ICP-OES and ICP-MS from acidified and filtered samples. Metal removal efficiency and regional differences were evaluated using the Wilcoxon test.

The OXA-48, KPC, NDM, and VIM genes were more abundant in sewage samples and persisted even after treatment in WWTPs. No statistical differences were observed between sample types (p > 0.05), suggesting variability. In affected areas, multidrug-resistant species predominated, whereas environmental microorganisms were more frequent in unaffected areas. Diversity between regions was similar. Phosphorus and sodium levels were higher upstream (p < 0.05), indicating local pollution. Potassium and aluminum showed increasing trends, while calcium levels did not differ between regions.

The presence of ARGs and metals in WWTPs highlights these facilities as critical points in the AMR dynamic. The findings reinforce the importance of integrated surveillance in environmentally impacted contexts, emphasizing the One Health approach.