Multi-drug resistant bacteria are living in hospital sink drainpipes, putting them in close proximity to vulnerable patients, warns a team of US researchers.
They have now investigated how the bacteria are colonising the sinks using a mock-up built in the lab, highlighting that the process was previously unclear.
“We wanted to better understand how transmission occurs”
The project grew out of the knowledge that patients were dying from infections with multi-drug resistant bacteria acquired while in hospital, said the study authors from the University of Virginia.
Along with researchers from Oxford University, they had initially carried out a review of studies to highlight the scale of the problem and that it was on the increase.
They reviewed more than 32 papers on the spread of bacteria resistant to the antibiotic carbapenem via sinks and other water reservoirs within hospitals, finding most were from after 2010.
For the new study, the US researchers built five identical sinks in their lab, modelling them on the most common intensive care unit sink in the university’s hospital in Charlottesville.
For their experiments with the sink, they used the bacteria Escherichia coli (E. coli), which though commonly harmless in the human intestinal tract, can acquire both pathological genes and antibiotic resistance genes, becoming superbugs.
Initially, the researchers found the bacteria colonised the elbows of the drain pipes. They showed that from there, the colonies grow slowly towards the sink strainers – at the rate of roughly one inch per day.
Given the distance in typical hospital sinks of elbows below the sink bowls, it frequently takes a week for the colonies to reach the sink strainers, said the study authors in the journal Applied and Environmental Microbiology.
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Source: Harry Moxley | UVA School of Medicine
From there, the suggested the bacteria quickly got splattered around the sink, and even onto the counters surrounding the sinks, where they could be picked up by the patients.
Study author Dr Amy Mathers, associate professor of medicine and pathology, said: “We wanted to better understand how transmission occurs, so that the numbers of these infections could be reduced.
“Our study demonstrates that bacterial spread from drainpipes to patients occurs via a staged mode of transmission,” she added.
The researchers said they would now use the sink lab – the only one in the US – to conduct a follow-up study to try and determine precisely how the pathogens reach the patients.
Dr Mathers said: “This type of foundational research is needed to understand how these bacteria are transmitted so that we can develop and test potential intervention strategies that can be used to prevent further spread.”