The spread of antimicrobial resistance in the aquatic environment from faecal pollution: a scoping review of a multifaceted issue

Antimicrobial resistance (AMR) is a major global health concern accelerated by the misuse and mismanagement of antibiotics in clinical and veterinary settings, leading to longer treatment times, increased costs and greater mortality rates. The environment can play a major role as a source and disseminator of AMR, with faecal pollution, from both anthropogenic and non-anthropogenic sources making a significant contribution. The review aimed to identify how faecal pollution contributes to AMR in surface water, focusing on current methods of source tracking faecal pollution. The databases used were Medline Ovid® and Scopus. From the search, 744 papers from January 2020 to November 2023 were identified, and after the screening, 33 papers were selected that reported on AMR, aquatic environments and faecal pollution and were published in English. The studies were from six different continents, most were from Europe and Asia indicating faecal pollution is influenced by spatiotemporal differences such as population and sanitation infrastructure. Multiple different methodologies were used with a lack of standardised methods making comparability challenging. All studies identified AMR strains of faecal indicator bacteria showing resistance to a wide variety of antibiotics, particularly beta-lactams and tetracyclines. Few studies investigated mobile gene elements with class 1 integrons being the most frequently studied. Wastewater treatment plants were significant contributors, releasing large amounts of AMR bacteria into the environment. Environmental factors such as seasonal differences, temperature, rainfall and UV exposure, along with local antibiotic usage influenced the local resistome. Animals, both wild and domestic, introduced antimicrobial resistance genes and potential pathogens into the aquatic environment. Overall, faecal pollution is a complicated issue with multiple factors contributing to and facilitating the spread of AMR. Standardisation of methods and surveillance, robust wastewater management and further research into AMR dissemination are needed to address the human health, animal health and environmental concerns.