Wastewater monitoring used during the COVID-19 pandemic could also help track the spread of antimicrobial resistance.
Antimicrobial resistance, often shortened to AMR, happens when bacteria and other microbes evolve so that antibiotics and other medicines no longer work as well against them, the European Commission noted in a release on Friday.
AMR is projected to cause 1.91 million global deaths each year by 2050, according to Science for Environment Policy, an EU-funded news alert service summarising the research.
The review says “wastewater-based surveillance” — testing sewage for genetic traces of microbes — could offer a way to map trends and possible routes of spread for antibiotic resistance genes, the pieces of DNA that can allow bacteria to withstand treatment.
This approach could provide early warning of rising resistance levels in a community.
Evidence reviewed by the paper found links between the amount and variety of antibiotic resistance genes in wastewater and local conditions such as sanitation infrastructure and access to clean water.
Studies also identified regional differences in genetic profiles, with 49 common resistance genes detected across a range of environments.
Wastewater monitoring can be carried out at different scales, from a single building to an entire city, and can sample sewage from sources including hospitals, farms, pharmaceutical companies and municipal systems.
Practical and ethical hurdles
The paper said wastewater surveillance is most difficult to implement in places without central sewer networks, where non-sewered sanitation systems make sampling more complicated.
It also listed challenges including difficulties in linking specific resistance genes to the microbes carrying them, and problems standardising how samples are collected and analysed across different places.
Privacy concerns can arise because personal information may appear in raw datasets, particularly when samples come from small catchment areas.
The review concluded that wastewater-based surveillance could be used as a tool for tracking AMR if it is carried out consistently and systematically, and backed by international coordination and long-term investment.
The findings were published in "mBio" by researcher J. L. Balcázar in 2025.
