How do discharged antibiotics influence environmental antibiotic resistance?

The growing risk of antibiotic resistance threatens the advancements in healthcare made over the past 50 years. The environmental burden of antibiotic resistance is increasingly recognised as a contributor to the global resistance threat. Human use and consumption of antibiotics result in a fraction of unmetabolised drug passing through the patient. As this unmetabolised material is cleared from the patient it inevitably results in antibiotics being dispersed into the sewer system where they are subjected to bulk wastewater treatments such as activated sludge, anaerobic digestion and trickle-bed filters, which all utilise the biological activity of microbial communities. Treated material, often in the form of anaerobic digestate can then be applied to land as a nitrogen-rich fertiliser or finished treated wastewater, which can be used as alternative for freshwater irrigation in drought stressed regions.
Microbial communities will be sampled throughout the wastewater treatment process from arrival on site to discharge and in digestate and soils where this material is used to determine whether these drugs result in additional antimicrobial resistance (AMR) within environmental microbial communities. This project will utilise a range of molecular techniques to determine the concentrations, fate and influence of discharged antibiotics on the microbial communities that come into contact with this disposal route. Antibiotic concentrations will be measured using state-of-the-art mass spectrometry methods and the prevalence of antimicrobial resistance genes assessed using qPCR and NGS methods. Different wastewater treatment methods will be assessed for their effects on antibiotic removal and potential to propagate AMR genes through microbial populations.