Metagenomic profiling of hospital wastewater: A comprehensive national scale analysis of antimicrobial resistance genes and opportunistic pathogens

Background
Healthcare settings are recognised as potential hotspots for the emergence and spread of antimicrobial resistance (AMR).
Method
Metagenomic sequencing was conducted on a national scale using wastewater from hospitals across Wales to screen for antimicrobial resistance genes (ARGs) and opportunistic pathogens.
Results
The total abundance and diversity of ARGs varied significantly across the hospitals. Genes conferring resistance to aminoglycosides, beta-lactams, and Macrolide-Lincosamide-Streptogramin-class antibiotics were predominant, with distinct resistome patterns emerging spatially. OXA-type beta-lactamases were the dominant ARG types. Spatial variability was observed in the distribution of the "big five" carbapenemases (KPC, IMP, VIM, NDM, OXA-48-like) and mcr genes, as well as WHO-listed fungal priority pathogens and Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli (ESKAPEE) pathogens. Furthermore, antibiotic concentrations in the effluents often exceeded risk quotients, posing a substantial risk for AMR emergence.
Conclusions
Overall, the study highlights the effectiveness of combining wastewater-based epidemiology with metagenomics to gain critical insights into the distinct resistome and microbiome profiles in hospital settings. Tailored strategies are essential to mitigate the spread of antibiotics, clinically relevant ARGs and pathogens in these settings. This study underscores the necessity of implementing pre-treatment processes for hospital effluents before release into community sewers and environmental waters to curb the spread of these micro-pollutants.