The Role of Wastewater in the Spread of Antimicrobial Resistance in Hospitals

The Role of Wastewater in the Spread of Antimicrobial Resistance in Hospitals

In a recent study published in the Journal of Hospital Infection, researchers conducted a comprehensive analysis of the wastewater system at the University Hospital Limerick to identify sources of infection and antimicrobial resistance (AMR) genes. The study revealed that the dominant microbes in the wastewater had high levels of AMR genes, emphasizing the importance of regular cleaning and decontamination to prevent patient infections.

Antimicrobial resistance poses a significant challenge in healthcare, with multi-resistant drug infections becoming increasingly prevalent worldwide. Previous studies have shown that contaminated hand-washing sinks can contribute to outbreaks in hospitals. It is believed that patient-facing wastewater apparatus may serve as reservoirs for antimicrobial-resistant genes (ARGs) and infection-causing microorganisms, necessitating further research to identify these reservoirs and inform effective interventions to control infections.

The study aimed to understand the taxonomic and resistome profiles of the wastewater system, specifically focusing on multidrug-resistant hospital-acquired infection (HAI) outbreaks. The researchers conducted a large-scale metagenomic analysis of the wastewater microbiome in a large teaching hospital with a history of AMR detections and outbreaks. They analyzed pipe samples collected from patient rooms before the refurbishment of the hospital ward, as well as clinical isolates from patients who had acquired AMR infections while admitted to the ward.

The analysis revealed a wide microbial diversity in sinks, with less diverse communities found in toilets and showers. The dominant phyla in the wastewater system were Proteobacteria and Actinobacteria. While different microbial profiles were present in different samples, demonstrating the influence of human behaviors and activities, ARG profiles did not show significant differences across sample types. This suggests that ARGs are shared across different bacterial species, potentially through divergent evolution or horizontal transfer.

Comparing the profiles of the wastewater pipe samples and the patient isolates, the researchers found similarities and a significant number of shared ARGs. The study highlighted the possibility of genes being passed from the wastewater system to patients or vice versa, emphasizing the crossover between clinically relevant pathogens and microbes in hospital wastewater environments.

In conclusion, this study underscores the importance of identifying and characterizing reservoirs of antibiotic resistance in hospitals. The use of metagenomics provides valuable insights into resistance genes present in both environmental and clinical isolates. The findings suggest that active antimicrobial stewardship and reducing the usage of broad-spectrum antimicrobials could help lower the burden of AMR. Effective policies and interventions are crucial to controlling infection transmission in hospitals and mitigating the emergence of more resistant diseases.

Journal reference: Large-scale characterisation of hospital wastewater system microbiomes and clinical isolates from infected patients: profiling of multidrug-resistant microbial species. Kelly, S.A., O’Connell, N.H., Thompson, T.P., Dillon L., Wu, J., Creevey, C., Kiely, P., Slevin, B., Powell, J., Gilmore , B.F., Dunne, C.P. Journal of Hospital Infection (2023).

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