In daycare centers, infants come in close contact with each other, and contact, droplet, and mouth-to-mouth infections may occur owing to sharing of toys. Additional effective disinfection methods should be considered aside from wiping with disinfectants-including alcohol or sodium hypochlorite solution-for environmental disinfection of daycare centers. We aimed to examine the usefulness of hypochlorous acid water atomization in the effective disinfection of the classroom environment and toys at a nursery school. Environmental cultures of the nursery and toys were prepared to evaluate the species and bacterial load and to assess the contaminated areas. Staphylococcus aureus petri dishes were placed at high-frequency contact sites, and hypochlorous acid water was atomized to achieve a 0.03-ppm atmospheric chlorine concentration. After the atomization, the amount of S. aureus bacteria on the Petri dish and the changes in bacterial count isolated from the environment and toys were evaluated. Hypochlorous acid water atomization was performed for 5 h to avoid condensation. After a 3-h atomization, ≥99.99% of S. aureus was eliminated on petri dishes; furthermore, a significant disinfection effect was observed on environmental bacteria at least 1 h after atomization. For rubber and textile toys, the significant disinfection effect was observed 1 h after atomization, and for plastic toys, the effect was observed 3 h after atomization. Hypochlorous acid water atomization is a useful strategy to disinfect nursery school classrooms.

Background: Many of the pathogenic bacteria and fungi found in hospital environments form biofilms, which allow them to persist in the environment for long periods, posing a risk of hospital-acquired infections. Although the pathogens within biofilms often have reduced levels of drug susceptibility, the efficacy of disinfectants routinely applied against planktonic pathogens must be evaluated against biofilms as well. Our objective in this study was to determine the efficacy of treatment using slightly acidic hypochlorous acid water and to compare the results with sodium hypochlorite when both were used to disinfect Candida parapsilosis biofilms. Methods: C. parapsilosis in the planktonic or biofilm state was treated with each disinfectant. The number of viable cells that remained was determined, and scanning electron microscopy (SEM) of the disinfectant-treated biofilms was performed. Results: Compared with sodium hypochlorite, in a shorter period of time, hypochlorous acid water completely killed not only planktonic C. parapsilosis but also C. parapsilosis in a biofilm that had been formed for 72 h. SEM showed that both disinfectants were effective in removing the C. parapsilosis biofilm to some extent. Conclusions: Slightly acidic hypochlorous acid water appears to be an effective disinfectant against C. parapsilosis both in suspension and in biofilms.