Wastewater-Based Epidemiology for monitoring community derived antimicrobials and resistance genes: a one-year longitudinal study

Increasing understanding and awareness of antimicrobial resistance (AMR) is critical in tackling this growing global crisis. Wastewater-based epidemiology (WBE) is a promising approach to monitoring a range of AMR targets in communities through analysis of wastewater. This longitudinal study provides insight into antimicrobial (AA) usage within two communities in the South West of the UK, one city (Bath) and one town (Keynsham). AAs, including metabolites, from a range of different classes were quantified over the study period. Average loads of AAs were higher in Bath than for Keynsham (difference on average was 88 ± 6%) which reflected the larger population. Several AAs experienced seasonal fluctuations, such as the macrolides erythromycin and clarithromycin that were found in higher loads in the winter, whilst other AA levels, including sulfamethoxazole and sulfapyridine, stayed consistent over the study period. Several antimicrobial resistant genes (ARGs) were also studied within the city area, in order to determine how closely the abundance of these genes correlates with the levels of relevant AAs. Several genes including ermB, sul1 and intI1 were not found at statistically significant different loads in winter 2018/19 when compared to summer 2019. Due to relatively stable AA and ARG levels across 13 months monitoring time, no clear correlation was observed between absolute loads of ARGs and total loads of associated AAs by class. Hospital effluent within the city catchment was also investigated for AAs and ARGs. Several AAs were more common in hospital wastewater than in community wastewater, including sulfamethoxazole and trimethoprim. This work can help establish baselines for AA usage in communities, providing community-wide surveillance and evidence for informing public health interventions.