Unseen dangers: How hospital sinks become breeding grounds for pathogens

AvantGuard Inc. is addressing the critical role of hospital sinks in the spread of harmful pathogens, contributing to healthcare-associated infections and outbreak risks.

What connects every room in a hospital, allowing patients to share pathogens, and serves as an ideal environment for pathogens to grow and flourish? The plumbing system. Flushing a toilet on the sixth floor can create pressure changes that send microscopic air bubbles containing pathogens into rooms on the floors below.

Hopsital sinks harbour pathogens

Hospital sinks are ubiquitous and are essential for promoting hygienic practices such as hand washing.  However, they also serve as conduits for waste collection and disposal. Depending on the institution, sinks can be exposed to diverse waste types, including beverages, sputum, animal or human blood, and even faecal matter. The waste flowing through sinks often contains essential nutrients such as water, carbohydrates, proteins, and lipids that support pathogen growth and help spread them to other environments. In a study of sinks in four acute-care hospitals in the US, 25% (12/50) of the sinks were found to harbour fluoroquinolone-resistant gram-negative bacilli.¹ Similarly, another study in a Swiss hospital discovered contamination of the drain and p-trap of sinks in an intensive care unit by carbapenemase-producing Pseudomonas aeruginosa.²

Pathogen spread from sinks to nearby surfaces

Unfortunately, pathogens present in hospital sinks are not contained in the plumbing system. Factors such as sink basin depth and water flow rate can cause fluids from sinks to spread pathogens to nearby surfaces. Regardless of water flow rate in a sink, 30 seconds of running hot or cold water from a faucet was enough to trigger the spread of pathogens from sinks to adjacent environmental surfaces.¹

Linked to outbreaks

Hospital sinks have been linked with disease outbreaks. A retrospective analysis of 552 intensive care units in Germany revealed that the risk of acquiring healthcare-associated infections was higher for patients with sinks in their rooms compared to those without sinks.³  In one disease outbreak investigation involving beta-lactamase-producing P. aeruginosa, researchers found that sinks in the washroom of intensive care units were the most likely source of the pathogen of concern.⁴ Similarly, an outbreak of extended-spectrum beta-lactamase-producing Klebsiella oxytoca was linked to contaminated handwashing sinks.⁵ In outbreaks where contaminated sinks are implicated, drains could be colonised for up to three years.⁶ These findings suggest that sinks may be reservoirs for pathogens and may present health risks.

Food safety issue too

The problem is not limited to hospitals. Food processing plants also face challenges with sinks and drains, which serve as connections to the outside world and the sewer system. Pathogens like Listeria are known to harbour in drainage.⁷ Combatting pathogens that travel up drains requires significant effort to ensure food safety.

Sink disinfection strategies

In response to outbreaks or increases in healthcare-associated infections linked to hospital sinks, some hospitals have implemented strategies such as regularly replacing sinks and plumbing, installing heaters on drains to kill pathogens by periodically raising the temperature, disinfecting on a more regular basis, or even removing sinks, particularly from intensive care units. While these measures have helped to ‘reverse’ disease outbreaks, they may not be effective in preventing pathogen buildup in sinks.

Difficulty of killing pathogens in sinks

The persistence of pathogens in sink drains is often due to the establishment of biofilms, communities of microorganisms encased within a protective layer of organic material. Sinks continue to be linked with outbreaks because biofilms are approximately 1,000 times harder to kill than microorganisms without a biofilm. Eliminating biofilms requires (1) a high concentration of disinfectants or (2) extended contact time.

High concentrations of currently available disinfectants strong enough to kill biofilms in sinks can cause corrosion, making that approach problematic. Very few currently available disinfectants have an EPA biofilm efficacy claim in their claim set. One product is a chlorinated disinfectant that is made from a tablet using NaDCC, also known as sodium dichloroisocyanurate, as opposed to bleach or sodium hypochlorite.  That product has a biofilm claim with a four-minute contact time at about 4,000 ppm, which is a higher level of chlorinated disinfectant than most users are comfortable with for regular use on surfaces because of fear of corrosion.

Achieving a several-minute contact time is also difficult for this particular use case. The vertical nature of the drains means that holding material on the surface is challenging.  Many products have a foaming or gel-like implementation to extend the wet contact time. The contact time while wet is critical since most currently available disinfectants lose effectiveness as soon as they dry, requiring repeated application to maintain a pathogen-free environment.

Next generation sink disinfectant

AvantGuard’s new disinfectant, Avantamine, is non-corrosive at high concentrations and continues to provide lasting protection against re-contamination for days after drying. Avantamine can be implemented into a product form with a gel-like consistency that thoroughly coats the sink and drain, first killing pathogens and their biofilms and then leaving a long-lasting protective layer.

Avantamine is best described as doing for chlorine what povidone does for iodine to create povidone iodine. Tincture of iodine was the only form of iodine that could be used to apply iodine to a wound or the skin to kill pathogens. Povidone polymer was found to stabilise iodine, which increased the efficacy of iodine itself because of the reduction in non-specific activity. At the same time, povidone made the iodine safer for the skin by reducing irritation. Avantamine is a polymer that stabilises chlorine. In a sense, bleach is a tincture of chlorine, and Avantamine stabilises chlorine to reduce non-specific activity, which reduces the likelihood of corrosion and also reduces the likelihood of skin irritation.

Furthermore, the stabilisation of chlorine enables Avantamine to survive with the chlorine intact after drying.  This means that Avantamine can hold chlorine on a surface, safely, for long periods. These enhanced attributes, reduced corrosion and residual activity, do not come at a cost of efficacy, with Avantamine having almost identical pathogen killing activity to bleach.

Avantamine can come as a liquid or a gel. The gel formulation is ideal for this application since the gel will coat surfaces during application and provide the longevity needed for extended killing action. As an antimicrobial coating for drains, Avantamine meets and exceeds the U.S. Environmental Protection Agency’s required testing protocol for a residual disinfectant, protecting surfaces from pathogens for up to one week. Untouched, Avantamine can retain efficacy on environmental surfaces for over a month.

Avantamine’s low corrosion and residual efficacy combine to make a product that can eradicate biofilms in sinks and drains and provide continued protection for days against pathogen build-up and ultimately transmission. Protecting sinks and drains is just the first indication of this highly innovative biocide that addresses the problems of bleach while retaining the efficacy of bleach.

References

1. Gestrich, S. A.; Jencson, A. L.; Cadnum, J. L.; Livingston, S. H.; Wilson, B. M.; Donskey, C. J. A multicenter investigation to characterize the risk for pathogen transmission from healthcare facility sinks. Infection Control & Hospital Epidemiology 2018, 39 (12), 1467-1469.
2. Catho, G.; Martischang, R.; Boroli, F.; Chraïti, M.; Martin, Y.; Koyluk Tomsuk, Z.; Renzi, G.; Schrenzel, J.; Pugin, J.; Nordmann, P. Outbreak of Pseudomonas aeruginosa producing VIM carbapenemase in an intensive care unit and its termination by implementation of waterless patient care. Critical Care 2021, 25, 1-10.
3. Fucini, G.; Geffers, C.; Schwab, F.; Behnke, M.; Sunder, W.; Moellmann, J.; Gastmeier, P. Sinks in patient rooms in ICUs are associated with higher rates of hospital-acquired infection: a retrospective analysis of 552 ICUs. Journal of Hospital Infection 2023, 139, 99-105.
4. Cabal, A.; Hörtenhuber, A.; Salaheddin, Y.; Stöger, A.; Springer, B.; Bletz, S.; Mellmann, A.; Hyden, P.; Hartl, R.; Weinberger, J. Three prolonged outbreaks of metallo-β-lactamase-producing Pseudomonas aeruginosa in an Upper Austrian hospital, 2017–2023. Microbiology Spectrum 2024, 12 (10), e00740-00724.
5. Lowe, C.; Willey, B.; O’Shaughnessy, A.; Lee, W.; Lum, M.; Pike, K.; Larocque, C.; Dedier, H.; Dales, L.; Moore, C. Outbreak of extended-spectrum β-lactamase–producing Klebsiella oxytoca infections associated with contaminated handwashing sinks. Emerging infectious diseases** 2012, 18 (8), 1242.
6. Newcomer, E. P.; O’Neil, C. A.; Vogt, L.; McDonald, D.; Cass, C.; Wallace, M. A.; Hink, T.; Yerbic, F.; Muenks, C.; Gordon, R. The effects of a prospective sink environmental hygiene intervention on Pseudomonas aeruginosa and Stenotrophomonas maltophilia burden in hospital sinks. EBioMedicine 2025, 116.
7. Fairley, M. Hygienic design of floor drains in food processing areas. In Hygienic Design of Food Factories, Elsevier, 2023; pp 453-481.

Please note, this article will also appear in the 23rd edition of our quarterly publication.