Urban Wastewater Metagenomics Reveals the Antibiotic Resistance Gene Distribution Across Latvian Municipalities

Antimicrobial resistance (AMR) poses a global health threat, with urban wastewater systems serving as key reservoirs for resistance dissemination. This study aimed to investigate the relationships among urban environments, bacterial communities, and AMR patterns, and evaluate the specific municipal-scale drivers of resistance gene distribution. Shotgun metagenomic analysis was conducted on 45 wastewater samples collected from 15 municipalities across Latvia to determine the composition of the resistome and its correlation with local factors. The analysis identified 417 distinct antibiotic resistance genes (ARGs) belonging to 108 families, with geographic location serving as the primary driver of ARG distribution, which explained 65.87% of community variation (p = 0.001). Local industrial factors demonstrated significant effects, with food industry wastewater significantly influencing both bacterial taxonomy and ARG profiles (p < 0.05). While the presence of a regional hospital did not shape the overall municipal resistome, hospital-associated wastewater showed 19 overlapping ARGs, including clinically critical carbapenemases. Municipal wastewater systems function as geographically structured reservoirs of AMR that are shaped by localized industrial and healthcare outputs. These findings support wastewater-based AMR surveillance as a valuable tool for tracking specific resistance sources.