Correlation of Antibiotic Resistance Gene and Microbial Source Tracking Marker Removal through Activated Sludge Wastewater Treatment

Antimicrobial resistance (AMR) is a rapidly growing threat to human health, and wastewater treatment has also proven to be a hotspot for AMR selection and dissemination to the environment. Microbial source tracking (MST) targets potentially bridge existing gaps in monitoring AMR during wastewater treatment as indicators for a broad array of antibiotic resistance genes (ARGs). In this study, we compared the removal of bacterial and viral MST targets (E. coli, enterococci, somatic coliphage, human adenovirus, human polyomavirus, crAssphage, and HF183/BacR287), ARGs (sul1, sul2, ermF, tet(O), and tet(W)), and a mobile integron (intl1) through an activated sludge wastewater treatment process. Secondary wastewater treatment (i.e., activated sludge) accounted for the majority of observed ARG removal through the overall treatment process (84-100% of observed overall removal). Culturable indicators E. coli and enterococci were not well correlated with ARG or mobile integron removal. Conversely, culturable somatic coliphages demonstrated a strong correlation with ARG removal. The molecular indicator HF183/BacR287 demonstrated the most promise as an indicator for the suite of ARGs assessed in our study, highlighting the potential of MST markers as indicators of ARG fate during wastewater treatment.