No Flushing Them Away: Bacteria in Sinks and Restrooms

Sara Revolinski, PharmD, BCPS


January 30, 2019

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Sinks, Drains, Showers, and Baths

A recent article by Decraene and colleagues[1] describes an outbreak of Klebsiella pneumoniae carbapenemase (KPC)-producing carbapenem-resistant Enterobacteriaceae (CRE) infections on two wards within a major hospital in the United Kingdom. Literature-based infection control measures, including CRE screening of high-risk patients and patient cohorting, were implemented in 2014 in response to increased CRE infections. The affected wards were closed and terminally cleaned, and were decontaminated with hypochlorite and hydrogen peroxide vapor. In 2015, an outbreak involving KPC-producing Escherichia coli triggered implementation of enhanced infection prevention measures. Again, the wards were closed and environmental cleaning was undertaken. In addition, environmental sampling was introduced, with a total of 927 samples obtained throughout the hospital; 355 of those were taken from the affected wards.

Twenty-six samples (7%) from the affected wards were positive, with the majority of samples taken from sinks, drains, and shower and bath sites. In addition, sink trap replacements for colonized sinks occurred three distinct times throughout 2015, as did a one-time pipework cleaning to remove biofilms. Because of continued isolation of CRE from sink/drain sites and patient colonization, the plumbing structures were replaced (until they connected with the central drainage stacks). Despite this, sink and drain sites continued to test positive, and KPC-producing E coli continued to be isolated from patients.

Paper Towels vs Jet Air Dryers?

Another European study, by Best and colleagues,[2] evaluated bacterial contamination of hospital bathrooms based on the method of hand drying, using either paper towels or jet air dryers. This multicenter, crossover study was conducted in three hospitals, one each in the United Kingdom, Italy, and France. Two public restrooms per hospital, serving hospital staff, patients, and visitors, were evaluated. Hand-drying methods were alternated between restrooms, with a washout period of 2 weeks between the different methods. Footfall was measured in each restroom, mainly to ensure similar use. Bacterial contamination levels in the air, from dust (collected by vacuuming high and middle-height areas as well as the floor), and on surfaces (sink, doorplate, and floor under the drying unit) were measured once per day, 5 days per week, over the course of 12 weeks, for a total of 120 sessions per hospital.

Footfall was nine times higher in UK washrooms, and contamination in the UK and France restrooms was found to be higher than that in Italy. Although use of paper towels and jet air dryers was similar at each site, bacterial contamination was lower in paper towel compared with jet air dryer washrooms (median, 0-10 vs 100-300 colony-forming units; P < .0001). In the United Kingdom, methicillin-susceptible Staphylococcus aureus, methicillin-resistant St aureus, Enterococcus species, and extended-spectrum beta-lactamase producers were isolated significantly more from jet air dryer restroom surfaces compared with paper towel surfaces (P < .0001 for all). In France, extended-spectrum beta-lactamase producers were isolated from dust more frequently in jet air dryer compared with paper towel washrooms.


Just like microorganisms, infection control methods continue to evolve as we discover new reservoirs of infection and mechanisms of transmission. These two studies suggest that new targets for infection prevention may be related to handwashing.

In the first study, Decraene and colleagues demonstrated that hospital sinks and drains are important reservoirs of CRE, showing that traditional infection control procedures may be ineffective in preventing spread of CRE when these areas are colonized.

Best and colleagues found that the hand-drying method can affect the risk for airborne dissemination of bacteria in hospital restrooms; however, the effect of this on clinical outcomes for patients was not described.


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