A Resistance Persistence Index (RPI) for antimicrobial resistance in wastewater

Antimicrobial resistance (AMR) represents a critical global health challenge, exacerbated by the proliferation of resistance genes in wastewater environments. This study introduces a novel Resistance Persistence Index (RPI) that integrates existing risk assessment frameworks with persistence and mobility metrics of antimicrobial resistance genes (ARGs) in wastewater treatment plant (WWTP) influent. We evaluated samples collected across wet and dry seasons, focusing on the dynamics of ARG diversity, abundance, and their associations with human impact. Our findings indicate a significant increase in unique ARGs during the wet season, with "antibiotic inactivation" as the predominant resistance mechanism. Using Zhang et al.s ranking framework, we assessed the risk levels of various ARGs, revealing that while fewer high-risk ARGs were identified, they demonstrated substantial abundance. The RPI provided insights into how the combined effects of persistence and mobility influence the risk associated with different ARG families. This integrated framework offers a comprehensive tool for understanding and managing AMR in environmental settings, guiding future surveillance and intervention strategies.