Improvement and standardization of disinfection in hospital theatre with ultraviolet-C technology.

BACKGROUND: The level of disinfection between operating sessions is important to prevent cross-contamination risk in operating theatres. AIM: To assess the difference in microbial contamination between different disinfection levels, before (T0) and after (T1) application of a UVC device (UVC-D). METHODS: A cross-sectional study was conducted between December 2019 and August 2020 in a clinic. Three disinfection levels - no disinfection after surgery, after in-between cleaning, and after terminal cleaning - were compared to assess the reduction of microbial presence at T0 and T1 according to the use of UVC-D for 3-5 min per bedside. A total of 260 Petri dishes, divided into a preliminary phase followed by a probabilistic model-driven experiment, were used in three operating theatres, and colony-forming units (cfu) were counted. The Mann-Whitney test was performed in the preliminary phase to establish UVC exposure time. Using the probabilistic model, descriptive statistics and percentage and log10 reduction were calculated. The multivariate analysis of variance (MANOVA) for repeated measures was performed to verify the 95% statistical difference between T0 and T1, combined with the disinfection levels and different operating theatres. FINDINGS: The Mann-Whitney test showed no cfu difference between 3 and 5 min of UVC exposure time; the MANOVA test showed no significant difference between disinfection levels in T0 - T1 cfu reduction with a mean cfu reduction of 72% (95% confidence interval: 61.7-84.9) regardless of the disinfection level applied previously. CONCLUSION: UVC-D has improved environmental disinfection in all initial conditions. Together with the classic sanitizing procedures already present, it improves and standardizes the level of environmental hygiene.