Infection Control & Hospital Epidemiology (2018), 39, 1497–1498 doi:10.1017/ice.2018.176
Research Brief
Efficacy of automated disinfection with ozonated water in reducing sink drainage system colonization with Pseudomonas species and Candida auris
Scott Livingston BS1,2, Jennifer L. Cadnum BS2, Scott Gestrich MD2, Annette L. Jencson BS, CIC2 and
Curtis J. Donskey MD1,3 1Case Western Reserve University School of Medicine, Cleveland Ohio, 2Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio and 3Geriatric Research, Education, and Clinical Center, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio
(Received 14 May 2018; accepted 3 July 2018)
Sinks in healthcare facilities are a potential reservoir for the dis- semination of gram-negative bacilli and Candida spp.1–4 Addressing sink contamination is challenging because sink drai- nage systems provide a favorable environment for pathogen colonization and biofilm formation, but they are not amenable to cleaning and disinfection. Disinfection of sinks with agents such as bleach, acetic acid, and hydrogen peroxide have been effective in some studies.1,2 However, such approaches may be difficult to implement long-term due to the time and effort required and the caustic nature of agents such as bleach. Ozonated water has been reported to be effective in killing
many pathogens.5,6 However, information on the efficacy of ozonated water for sink disinfection is limited. Here, we examined the efficacy of a sink providing automated disinfection with ozonated water against established sink drainage system coloni- zation with Pseudomonas aeruginosa and Candida auris. The SmartFLO3 sink (Franke Kindred, Canada) includes fea-
tures designed to limit dispersal (eg, a 23-cm-deep bowl) and an enclosed electrode that causes ozonation (0.1–0.35 ppm) and formation of reactive oxygen species in dispensed water. The sink also provides an automated, programmable flush with increased concentration of ozonated water (0.9–2.5 ppm), typically every 4 hours. The sink used in these experiments had access ports in the P-trap and in the drainage pipe distal to the P-trap. According to the manufacturer, the concentrations of ozone produced by the sink are safe for human drinking or bathing and are noncaustic to drain pipes. We tested the efficacy of ozonated water (0.9–0.12 ppm ozone)
produced by the sink against a strain of Pseudomonas aeruginosa isolated from a sink at the Cleveland VA Medical Center and 3 strains of Candida auris (MRL#31102, MRL#31103, and AR- BANK#0381).7 For P. aeruginosa, we used the American Society for Testing and Materials (ASTM) Standard quantitative carrier
Author for correspondence: Curtis J. Donskey, MD, Geriatric Research, Education,
and Clinical Center 1110W, Louis Stokes Cleveland VA Medical Center, 10701 East Boulevard, Cleveland, Ohio 44106. Email:
Curtis.Donskey@
va.gov.
Cite this article: Livingston S, et al. (2018). Efficacy of automated disinfection with
ozonated water in reducing sink drainage system colonization with Pseudomonas species and Candida auris. Infection Control & Hospital Epidemiology 2018, 39, 1497–1498. doi: 10.1017/ice.2018.176
© 2018 by The Society for Healthcare Epidemiology of America. All rights reserved.
disk method (ASTM E2197-11).8 For C. auris, we used the method recommended by the Environmental Protection Agency.9 Five percent fetal calf serum (Remel, Lenexa, KS) was used as the organic load. After a 10-minute exposure, carriers were neu- tralized with Dey-Engley neutralizer (Remel). The experiments were repeated in triplicate. The concentration of ozone was measured using an ozone test kit, model OZ-2x (Hach Company, Loveland, CA). We examined the efficacy of automated disinfection with
ozonated water in reducing established sink colonization with P. aeruginosa and C. auris. To establish colonization, the ozone generator was turned off and 106 colony-forming units (CFU) of both organisms were inoculated into the P-trap; the water was run for 30 seconds every 4 hours, and 25mL of tryptic soy broth was poured down the drain once daily. Cotton-tipped swabs were used to sample the P-trap, the port distal to the P-trap, and the proximal sink drain to a depth of 2.5cm below the strainer every 24 hours. Colonization with both organisms was established throughout the system and was maintained for at least 1 week before the ozone generator was turned on with continued expo- sure to water and tryptic soy broth. Sampling continued every 24 hours for 14 days; cultures were collected 4 hours after ozone flush disinfection. The swabs were vortexed in 1mL of Dey- Engley neutralizer, serially diluted, and plated onto MacConkey agar and Sabouraud dextrose agar (Becton-Dickinson, Sparks, MD) to quantify P. aeruginosa and C. auris, respectively. The experiment was repeated twice. On steel discs, each of the pathogens was reduced by ≥3.1
log10CFU with 10 minutes of exposure. During the sink coloni- zation process, both pathogens were detected distal to the P-trap within 5 days and at the strainer within 13 days after inoculation. Once established, the concentrations of the pathogens at each sampling site remained stable during the week prior to turning on the ozone generator. Figure 1 shows the concentrations of the pathogens in the
strainer, the P-trap, and the pipes distal to the P-trap at baseline and during the 14-day period of exposure to ozonated water for one of the experiments. The results for both sets of experiments were similar. At baseline, the concentration of P. aeruginosa at each sample site was ~5–6 log10CFU per swab, whereas C. auris
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