Combating antimicrobial resistance through wastewater “fingerprinting”: Surveillance and environmental risk assessment of antimicrobial usage in Welsh hospitals and communities

Antimicrobial resistance (AMR) has been identified by the World Health Organization among the top 10 greatest threats to global health [1]. Consumption of antibiotics results in antibiotic residues and their metabolites entering wastewater, where their continued presence, even at low concentrations, has been shown to exert a selective pressure on bacteria leading to increased antibacterial resistance [2]. Further, hospital wastewater can contain significantly higher concentrations of antibiotics [3] posing ecotoxicological risks [4]. The aim of this research is to investigate the spread of AMR via wastewater by comparing antimicrobial residue prevalence data with AMR data (i.e., prevalence of antibiotic resistant genes). For antimicrobial residue surveillance, over 275 wastewater samples were collected from 15 sites (influent from 8 community wastewater treatment plants and effluent from 7 hospitals) across Wales during two 3-month sampling campaigns—a summer campaign (May-July 2023) sampling 5 consecutive days per week each month, and a winter sampling campaign (Dec. 2023-Feb. 2024) sampling 3 consecutive days per week each month from selected sites. Using a validated UPLC–MS/MS method, over 120 antimicrobials and metabolites were quantified from numerous classes including: quinolones, beta-lactams, macrolides, sulfonamides, tetracyclines, antifungals, and antivirals. This comprehensive assessment presents a spatial evaluation of antimicrobial usage across Wales, and identifies seasonal trends. Surveillance data from a smaller selection of antimicrobials during the summer sampling campaign will be presented with a focus on the ecotoxicological risks. Interim results support the hypothesis that hospital wastewater is an area of concern as antimicrobial concentrations are significantly higher than community wastewater across numerous antimicrobial classes. During this time period, three hospitals had sulfamethoxazole concentrations which were more than double the predicted no-effect concentration for antibiotic resistance selection (PNEC-RS), and over 50-fold higher than the predicted no-effect concentration for ecotoxicity (PNEC-Eco) [5]. For clarithromycin, the overwhelming majority of community sites and all hospital sites exceeded the PNEC-RS, with one hospital having concentrations exceeding the PNEC-Eco by >1500-fold on numerous days [5]. These results confirm the importance of hospitals as hotspots of AMR.

References

1. World Health Organization, Ten threats to global health in 2019, https://www.who.int/news-room/spotlight/ten-threats-to-global-health-in-2019, (accessed May 3, 2023).
2. Gullberg, E.; Cao, S.; Berg, O. G.; Ilbäck, C.; Sandegren, L.; Hughes, D.; Andersson, D. I.; PLoS Pathogens, 2011, 7, e1002158. https://doi.org/10.1371/journal.ppat.1002158
3. Rodriguez-Mozaz, S.; Chamorro, S.; Marti, E.; Huerta, B.; Gros, M.; Sànchez-Melsió, A.; Borrego, C. M.; Barceló, D.; Balcázar, J.L. Water Res., 2015, 69, 234-242.https://doi.org/10.1016/j.watres.2014.11.021
4. Verlicchi, P.; Al Aukidy, M.; Galletti, A.; Petrovic, M.; Barceló, D. Sci. Total Environ., 2012, 430, 109-118.https://doi.org/10.1016/j.scitotenv.2012.04.055
5. Bengtsson-Palme, J.; Larsson, D. G. J. Environ. Int., 2016, 86, 140-149.https://doi.org/10.1016/j.envint.2015.10.015