City’s infectious disease treatment with antimicrobial agents – a longitudinal one year study of antimicrobials in two cities via wastewater-based epidemiology

Antimicrobial resistance (AMR) is one of the most significant global health threats. Inappropriate and over-usage of antimicrobial agents (AAs) is a major driver for AMR. Wastewater-based epidemiology (WBE) is a promising tool for monitoring AA usage in communities. Two urban catchment areas have been investigated in this study, one city and one small town in the Southwest of the UK over a 13-month period in 2018-2019. Population normalised loads (PNDLs) of 17 AAs and metabolites have been calculated and compared to catchment specific prescription data. Correction factors (CFs) have been applied to several AAs and metabolites in order to back-calculate consumption at the community level and compare to the corresponding catchment prescription data. Results have demonstrated positive correlations for all quantifiable parent AAs and metabolites in wastewater, and spatial variability in AA usage was observed even in neighbouring urban areas. The application of correction factors demonstrated good agreement for several of the studied AAs, including clarithromycin, oxytetracycline, trimethoprim, hydroxy metronidazole, and acetyl sulfamethoxazole. It was noted that in general, the larger population city gave closer agreement to estimated prescription intake than the smaller town. Differences in wastewater and between prescription data could be due to variable prescribing patterns and potential lack of compliance of AAs at the community level. This study has demonstrated that data triangulation, of both prescription data and wastewater data, provides the most comprehensive approach to understanding AA usage in communities.