Can Wastewater-based Surveillance Relate Antimicrobial Use to Resistance Patterns? Metagenomic Analysis of Two Neighboring Treatment Plants

Minimization of the use of antimicrobials is a recommended strategy to reduce the evolution and spread of antibiotic resistance; however, challenges remain in assessing the efficacy of such interventions. Wastewater-based surveillance (WBS) provides a promising means to consider differences in antibiotic resistance profiles across communities as a function of such interventions. We examined the metagenomes of sewage entering two neighboring wastewater treatment plants (WWTPs) serving a university and a nearby community. We compared antibiotic resistance gene (ARG) profiles as a function of data available for diagnoses of COVID-19 and other illnesses, clinical antibiotic use, antibiotic/antimicrobial and disinfectant/quaternary ammonium compound (QAC) concentrations in sewage, water quality indicators, and COVID-19-related behavioral shifts. Outpatient antibiotic prescription rates were consistently higher in the community than in the university zip code, but dropped markedly in both towns in April 2020, as COVID-19 lockdowns ensued. Antibiotic and QAC concentrations in sewage were consistent with these trends. Diversity and abundances of ARGs unique to the corresponding sewage were consistently higher for the community WWTP, but converged in 2022 when there was a surge in antibiotic prescriptions in the university zip code in response to elevated respiratory illness. Decreases in ARG diversity/abundance were not apparent during periods of decreased antibiotic usage, indicating a lag between antibiotic use and ARG wastewater signal.