A study conducted at a hospital in Ireland highlights the potential for hospital wastewater systems to serve as a reservoir for clinically relevant antibiotic-resistant pathogens, researchers reported last week in the Journal of Hospital Infection.
In the study, which was conducted at University Hospital Limerick, researchers performed a large-scale metagenomic analysis of wastewater pipes from a soon-to-be refurbished ward that has experienced multiple multidrug-resistant healthcare-associated infection outbreaks. For the analysis, they processed biofilm and extracted DNA from 20 pipe samples from patient rooms, including toilet u-bends and sink and shower drains. They also analyzed clinical isolates from patients who had been on the ward prior to refurbishment and were known to be colonized with antibiotic-resistant bacteria.
if we can stop these reservoirs from being established by improved infection control practices, we can hopefully stop patients from acquiring difficult-to-treat infections.
Sequencing of DNA from the pipe samples revealed a diverse reservoir of antibiotic-resistance genes (ARGs), and the most ARGs observed were those encoding resistant to commonly used antibiotics, including tetracyclines, fluoroquinolones, beta-lactams, and macrolides. Similarly, a diverse range of ARGs was identified in the clinical isolates, and a comparison of the clinical isolates with DNA from the wastewater pipes revealed a considerable number of identical ARGs.
"Whilst these data do not enable us to determine if resistance genes were transferred from patient to the wastewater system or indeed vice versa, they do allow us to confirm crossover in the resistome of clinically-relevant pathogens and the microbiome of the wastewater environment," the study authors wrote.
Since all pipes and drains from the hospital's wastewater system connect to the same sewage system, the authors say the findings suggest the system forms a "wastewater highway" that could spread the resistant bacteria from sinks, shower drains, and toilets throughout the hospital—a finding they believe could influence the hospital's infection control and cleaning strategies going forward.
"Such sites pose a risk for healthcare-associated infections, and if we can stop these reservoirs from being established by improved infection control practices, we can hopefully stop patients from acquiring difficult-to-treat infections," study co-author Nuala O'Connell, MD, of the University of Limerick said in a university press release.