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Effectiveness of a chlorine dioxide-based coating on environmental contamination in long-term-care facilities

      To the Editor:
      The increasing prevalence of multidrug resistant organisms (MDROs) in acute care hospitals has heightened concerns about the role of long-term-care facilities in amplifying the burden.
      • Luk S.
      • Ho A.Y.M.
      • Ng T.K.
      • Tsang I.H.L.
      • Chan E.H.Y.
      • Choi K.W.
      • et al.
      Prevalence, Prediction, and Clonality of Methicillin-resistant Staphylococcus aureus Carriage at Admission to Medical Units in Hong Kong, China.
      The role of environmental contamination in MDROs transmission is evident. New technology, such as hydrogen peroxide vapor fumigation, is promising
      • Passaretti C.L.
      • Otter J.A.
      • Reich N.G.
      • Myers J.
      • Shepard J.
      • Ross T.
      • et al.
      An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms.
      ; however, the method does not prevent subsequent microbial recontamination. Chlorine dioxide is an Environmental Protection Agency-registered gaseous sterilant that oxidizes the cytoplasmic membrane and denatures proteins of microorganisms.
      • Ogata N.
      Denaturation of protein by chlorine dioxide: oxidative modification of tryptophan and tyrosine residues.
      Through sustained release of gaseous chlorine dioxide from a polymer-microencapsulated liquid coating, long-term disinfection of surfaces up to 28 days could be demonstrated.
      • Leung W.K.
      • Lau A.P.
      • Yeung K.L.
      Bactericidal and sporicidal performance of a polymer-encapsulated chlorine dioxide-coated surface.
      To evaluate the efficacy of this coating in reducing surface microbial loads and vancomycin-resistant enterococci (VRE) contamination in the environment, a controlled before-and-after study was undertaken in the room environment of 3 VRE carriers in 3 long-term-care facilities between October 2012 and March 2013.
      The room environment of another 3 residents with matched functional status in the same facility was chosen as the control. The environmental surfaces were cleaned twice daily with chorine-based solution (500 ppm) in the 7-week pre- and postintervention periods. During the 10-week study period, weekly application of chlorine dioxide coating (7,960 ppm) (Greenland Biotech Ltd, Hong Kong, China) was performed in the room environment of the VRE carriers by wiping, in addition to standard environmental cleaning regimens that varied among the facilities and included daily cleaning with chlorine-based solution (500 ppm) in Facility A, twice daily cleaning with tap water in Facility B, and daily cleaning with diluted (1/20 strength) chlorine dioxide coating (398 ppm) in Facility C. Twenty environmental sites were sampled on the same day of each week between 10 AM and 12 PM (ie, before the first time cleaning).
      Only 6 of 212 sites remained coated with chlorine dioxide after 1 week (2.8%; 95% confidence interval, 1.3%-6.0%). The median total aerobic count of the chlorine dioxide-coated surfaces (n = 155) was similar to that of uncoated surfaces (n = 276) (median, 2.70 vs 2.63 CFU/cm2; P = .68). Bedside tables were the most heavily burdened objects, with a maximum aerobic count of 50 CFU/cm2, 20 times higher than the benchmark level for transferring pathogens (Fig 1). Only the coated light switches of Facility C showed significantly reduced microbial burden by 17 times (median, 0.04 vs 0.7 CFU/cm2; P = .046) (Fig 1). The VRE carrier residing in the room was bedbound and therefore was postulated to use the light switches infrequently. Of note, VRE was isolated not uncommonly in the immediate environment of VRE carriers (5%), especially for residents who are dependent on caregivers for daily activities (7% difference; P = .008). The presence of VRE on frequent-touch surfaces may contribute to its cross-transfer if proper hand hygiene is not practiced. The potential contamination of hands during the hand-washing process by a VRE-contaminated sink tap was of particular concern. This highlights the important role of self-disinfecting surfaces that could reduce the dependency on proper cleaning practices. Chlorine dioxide coating did show a trend of reducing the prevalence of VRE contamination by 54%, although this did not reach statistical significance (P = .16). The application of chlorine dioxide coating was therefore potentially advantageous for patients harboring MDROs such as VRE in reducing the environmental contamination.
      Figure thumbnail gr1
      Fig 1Comparison of total aerobic count (in colony forming units/centimeters2) among rooms of control patients (light bars) and vancomycin-resistant enterococci carriers (dark bars) in combined preintervention and postintervention periods and intervention periods. Reduction in the total aerobic count is significantly different (P < .05).

      References

        • Luk S.
        • Ho A.Y.M.
        • Ng T.K.
        • Tsang I.H.L.
        • Chan E.H.Y.
        • Choi K.W.
        • et al.
        Prevalence, Prediction, and Clonality of Methicillin-resistant Staphylococcus aureus Carriage at Admission to Medical Units in Hong Kong, China.
        Infect Control Hosp Epidemiol. 2014; 35: 42-48
        • Passaretti C.L.
        • Otter J.A.
        • Reich N.G.
        • Myers J.
        • Shepard J.
        • Ross T.
        • et al.
        An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms.
        Clin Infect Dis. 2013; 56: 27-35
        • Ogata N.
        Denaturation of protein by chlorine dioxide: oxidative modification of tryptophan and tyrosine residues.
        Biochemistry. 2007; 46: 4898-4911
        • Leung W.K.
        • Lau A.P.
        • Yeung K.L.
        Bactericidal and sporicidal performance of a polymer-encapsulated chlorine dioxide-coated surface.
        J Appl Microbiol. 2009; 106: 1463-1472