AMR pollution dynamics determined by the untreated wastewater domination of both the hydrology and point source loads to the Musi River, Hyderabad

Antimicrobial resistance (AMR) is a silent pandemic, which is transmitted and spread through the environment. Throughout the global south, large urban areas interact with, and often exert considerable control on, both the hydrological and pollution dynamics on the rivers they are built around. Despite this, little is known about the prevalence, sources, and transport of AMR through these common, yet complex environments. Here, we quantified taxonomic and resistance genes (ARGs), sensitive and resistant bacteria (ARBs), and environmental conditions in both river water and sediment along the Musi River in Hyderabad, a city renowned for antimicrobial manufacturing and urban dominance of the river environment. We also developed estimates of urban wastewater inputs and a hydraulic model to understand the rapid changes in river flow and pollution concentrations occurring along the river length through the city. This reveals increasing, though variable, concentrations in ARGs along the river through the dry season, and stronger discrete point source and flow dilution dynamics in the wet season. The riverbed sediment stores far higher concentrations than the water column, especially in the dry season, and has more dynamic interaction with the river during the wet season. This study reveals the importance of both flow and removal dynamics in controlling AMR prevalence in the environment, in a context that is both common and expanding throughout the global south.