Assessment of the risk of dissemination of environmental antibiotic resistance to human pathogens in aquatic ecosystems

2026-07-22

Antibiotic resistance is a major global public health threat. There is a growing concern that aquatic environments, which are in contact with the human microbiome in both urban and rural settings (drinking water, recreational bathing, crop irrigation), may serve as a reservoir of antibiotic resistance genes (ARGs) that might disseminate to human pathogens through horizontal gene transfer (HGT). However, the magnitude of this dissemination risk and the mechanisms involved remain unknown. REWARD (REsistance to antibiotics in Water: Assessment of the Risk of Dissemination) aims to identify the major drivers of human health risk and establish biomarkers for the monitoring and mitigation of antibiotic resistance dissemination in aquatic environments. REWARD will fill current knowledge gaps on the prevalence and ARG content of mobile genetic elements (MGE, plasmids and bacteriophages) in the aquatic environment, the frequency and genetic responses driving ARG HGT from these MGE to human pathogens, the impact of environmental and anthropogenic stresses on MGE prevalence and HGT frequency and the magnitude of the ARG dissemination risk to human pathogens in aquatic ecosystems. River and sea water from 8 aquatic ecosystems across Europe will be analyzed. The main drivers (MGE and genes) of ARG dissemination to fluorescent-labelled human pathogens added to surface waters will be determined using a combination of flow cytometry, last-generation metagenomic and metatranscriptomic sequencing technologies and newly-developed bioinformatic approaches for the reconstruction of MGE from metagenomic reads. Physiochemical and anthropogenic variables will be characterized in river water samples to establish dose-response links between anthropogenic and environmental stresses (including stresses linked to climate change) and ARG HGT in aquatic environments. Finally, a mathematical model to quantitively predict ARG dissemination risk will be developed using the data generated in REWARD.

Denmark

2026-01-01