Bacteria in hospital sinks: the plumbing that can sicken

Contaminated sinks

Sink design may be an underestimated factor regarding the incidence of bacterial infections, particularly in clinical settings. A new UK study sheds light on how bacteria in hospital sinks can grow and spread. The findings also highlight the importance of hygiene measures and awareness amongst medical professionals.

It’s a research study that may make you reconsider not only what’s inside your sink, but what’s anywhere near it. In a newly published study in The Journal of Hospital Infection, a UK-based research team found evidence that carbapenem-resistant Enterobacteriaceae (CRE, or carbapenemase-producing Enterobacteriaceae (CPE)) were shown to make their way from contaminated drains to sink and surrounding surfaces via splashback – and that this bacteria can travel quite a distance.

For over two decades researchers have known that hospital sinks and drains can support long-term persistence of multidrug-resistant Enterobacteriaceae and other gram-negative organisms. More recently sinks, drains and waste traps have been found to harbor identical or very similar CRE strains as those infecting patients. Based on this, some studies have concluded that these environmental reservoirs represent a source for CRE colonisation and infection of patients, or a persistent source in between patient-related outbreaks.

How CRE can spread from hospital sinks

The UK-based researchers, led by Dr. Paz Aranega-Bou of Public Health England, investigated two factors in the spread of CRE from sinks: the position of the drain in relation to tap outlet and draining conditions. The team recreated the environment found in many modern clinical settings, with a large-scale model sink system. Its waste traps were colonised with CRE taken from a hospital. At the same time, new waste traps were installed and artificially inoculated with CRE. The researchers also considered the potential for bacteria to be dispersed from hospital sinks by using cyclone air samplers and/or settle plates.

Better design = better health?

The researchers confirmed that flaws in sink design have health consequences: Slow drainage rates and sink designs with the drain directly underneath the tap increase the risk of CRE in waste traps and drains to contaminate hospital wards. Most of the dispersed bacteria were concentrated on surfaces immediately surrounding the sink, where the risk for cross-contamination is highest. However, the UK study demonstrates another crucial factor: CRE-containing droplets originating from a sink can be dispersed up to one meter. The researchers conclude that this possibility should be considered when designing hospital rooms, whether for patients or storage. While rear-draining sinks can help prevent bacterial spread, appropriate sink usage and maintenance of the water and drainage system are also essential.

Though the current evidence is preliminary, it raises the importance of a comprehensive approach to hygiene, including surface and hand disinfection. At least two factors have to be considered: clinical design – of plumbing, sinks and the surface areas outside of them – alongside human behavior: how medical professionals, staff, patients and visitors are interacting with these design elements. People need to be aware of possible bacterial contamination at the hospital sink areas, in order to improve surface and hand hygiene measures. Overall, this study suggests that a multi-faceted approach to hygiene can reduce contamination – wherever it lurks.

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