Infection Control & Hospital Epidemiology
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included Pseudomonas aeruginosa (n=7), Stenotrophomonas maltophilia (n=1), Proteus mirabilis (n=1), and Enterobacter agglomerans (n=1). All control cultures of the countertop and hands and of water from the faucet were negative. As shown in Figure 1, the sink drain cover significantly reduced
Fig. 1. Pictures of personnel performing hand washing (A) and of visible water splattered onto the cover gown after hand washing (B).
the frequency of contamination. Because gram-negative bacilli were dispersed from 2 sinks despite the presence of the drain cover, we assessed potential reasons for the failure of the device. For both sinks, it was observed that water inflow from the faucet was faster than water outflow such that water backed up in the sink bowl. To examine the potential for dispersal, 1 mL fluorescent gel was inoculated just below the strainer of each sink, the drain cover was installed, and the water was run for 15 seconds. Water backed up into the sink bowls and drain covers, and a black light was used to demonstrate fluorescent gel dispersal to sink bowls and countertops and to gowns of personnel.
Discussion
Recent studies have demonstrated that gram-negative bacilli and Candida spp can be dispersed from colonized sink drains to envi- ronmental surfaces outside the sink bowl.1–4 In the current study, we have demonstrated that such dispersal can also result in con- tamination of the clothing and hands of individuals washing their
hands.This mechanism of dispersal could lead to contamination of healthcare personnel and patients. Our findings are consistent with previous evidence that sink drain
Fig. 2. Percentage of sink countertops, cover gowns, and hands with positive cultures for gram-negative bacilli after washing hands for 15 seconds with versus without a plastic sink drain cap in place. *, P ≤ .03.
laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy.9 If multiple colony morphologies were present, only the predominant colony morphology was tested. For the initial 20 sinks studied, 50mLwater from the faucet was
filtered and the filter paper was cultured for gram-negative bacilli. The Fisher exact test was used to compare the proportions of contamination with and without the drain cover in place.
Results
Of 112 sink drains cultured, 109 (97%) had growth of gram- negative bacilli extending to the third and/or fourth quadrants of the culture plates. All drain cultures included colonies consistent with Pseudomonas spp or other non–lactose-fermenting gram- negative bacilli, but presence of multiple colony morphologies was common. Figure 2 shows percent contamination of counter- tops, cover gowns, and hands after hand washing with versus without the sink drain cover for the 109 colonized sinks. Without the drain cover, there was no significant difference in the percent- age of contaminated countertops and cover gowns or hands: 12 of 109 (11%) versus 10 of 109 (9%) versus 6 of 109 (6%; P ≥ .22). The median numbers of colonies recovered from countertops, gowns, and hands were 2, 5, and 4, respectively. For 8 of 10 sinks associated with gown and/or hand contami-
nation (80%), the organisms recovered from the gown or hands were the same species as the predominant isolate recovered from the sink drain; organisms recovered from the gown and/or hands
covers could reduce pathogen dispersal from sinks.8 However, the results also highlight a potential limitation of the drain covers. The devices did not prevent dispersal from 2 sinks where there was evidence of back up of water into the sink bowl and device due tomore rapid inflowthan outflowof water.Kotay et al4 similarly demonstrated dispersal of bacteria from below the strainer when water backed up due to a higher inflow than outflow of water. Thus, sinks with drain covers should be examined to determine whether there is the potential for water backup. Our study has some
limitations.The studywas conducted in only
1 hospital. However, similar dispersal of gram-negative bacilli has been demonstrated in sinks in 4 hospitals.10 The sink drain cover was only tested for 1 hand-washing episode per sink. However, we previously implemented the devices for a 2-week period in an intensive care unit and demonstrated that organisms in the sink bowl can be dispersed by flowing water.4 Thus, our results may underestimate the frequency of dispersal because the sink bowl was disinfected prior to hand washing. Finally, additional studies are needed to determine whether dispersal to clothing and hands contributes to transmission in healthcare facilities.
Acknowledgments. We thank the nursing staff of the Cleveland VA Medical Center for assistance in coordinating the timing of the study assessments.
Financial support. This work was supported by the Department of Veterans Affairs. Boehringer Laboratories provided the drain covers that were used but did not provide funding or input on study design and did not review the manuscript.
Conflicts of interest. C.J.D. has received research funding from Clorox, EcoLab, GOJO, Pfizer, Avery Dennison, and Boehringer Laboratories. All other authors report no potential conflicts relevant to this article.
References
1. Kanamori H, Weber DJ, RutalaWA. Healthcare outbreaks associated with a water reservoir and infection prevention strategies. Clin Infect Dis 2016;62: 1423–1435.
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