ABSTRACT
DDW 2022 Author Disclosures: KUMIKO UCHIDA: NO financial relationship with a commercial interest ;Takao Itoi: NO financial relationship with a commercial interest ;Masakatsu Fukuzawa: NO financial relationship with a commercial interest ;Akira Madarame: NO financial relationship with a commercial interest ;Takashi Kawai: NO financial relationship with a commercial interest Background: The outbreak of coronavirus infection (COVID-19) in 2020 has not yet ended in Japan and overseas, and droplet, contact, and aerosol infections have been suggested as routes of COVID-19 infection. As COVID-19 infection spreads, supply and demand for alcohol disinfectant solutions are temporarily tight, and hypochlorous acid water has attracted attention as a material available to the consumers.Purpose: The purpose of this study was to evaluate the environmental bacteria in an endoscopy unit sprayed with hypochlorous acid water from the viewpoint of space purification as an infection control for aerosols. Methods: An unmanned endoscopy unit was used after the end of a day's work. The viable counts of environmental bacteria in the cleaning group (before and after normal cleaning) and in the spraying group (before and after spraying with hypochlorous acid water) were compared and examined. Sampling of adherent bacteria (environmental bacteria) on beds, floors, illuminating apparatus for endoscope, PC desks, and washbasins, which are considered to be exposed to aerosols, was evaluated using SCD agar medium (product name: Petan Check, manufacturer: Eiken Chemical Co., Ltd.). For normal cleaning, disinfectant solutions of quaternary ammonium, isopropyl alcohol, and 80% ethanol were use after the work was completed. The hypochlorous acid water was sprayed with IONLESSTM hypochlorous acid water (product name: CLFine, manufacturer: Nipro Corporation) in accordance with the working environment evaluation standard of the Industrial Safety and Health Act, and the atmospheric effective chlorine concentration was kept at about 0.03 ppm, which is considered to be the optimum concentration, for 5 hours. The Mann-Whitney U test was used to compare the number of adherent bacteria. Results: There was no difference in the number of bacteria on the bed, illuminating apparatus for endoscope, computer desk, and washbasin between the cleaning and spraying groups. The median number of bacteria on the floor before cleaning was 26 CFU/10cm2, while that after cleaning was 23 CFU/ 10cm2. On the other hand, in the hypochlorous acid water group, the median value before spraying was 27 CFU/10cm2 and after spraying was 4 CFU/10cm2. Although there was no statistical difference (p=0.057), the hypochlorous acid water group tended to have fewer adherent bacteria. Conclusion: The hypochlorous acid spray tended to reduce the number of adherent bacteria (environmental bacteria) on the floor where aerosol exposure was possible, and the hypochlorous acid spray was considered to be useful in reducing environmental bacteria in endoscopy unit.