Light at the End of the Tunnel! Effects of 405 nm Visible Light Disinfection on Surgical Site Infection: A Prospective Randomized Cohort Study

Introduction: Surgical site infections (SSIs) are a substantial contributor to morbidity and mortality rates. 405 nm visible light disinfection (VLD) has been shown to reduce bacterial burden in operating rooms (ORs); however, its effect on SSIs is poorly described. Therefore, we investigated whether the usage of VLD correlated with a decrease in SSI rates. Methods: A prospective cohort study was conducted by comparing three operating rooms equipped with VLD and three operating rooms equipped with standard lights. Bacterial loads within the six ORs of interest were obtained before and after initiation of VLD. Patients of various surgical subspecialties were randomly assigned to rooms. SSI rates were tracked from July 2019 to June 2022. The primary outcome of interest was the SSI rate. Results: A total of 11,381 patients were included in the study, comprising 5,036 in VLD rooms and 6,345 in control rooms. Although age, gender, and body mass index were similar between the groups, there were differences in American Society of Anesthesiologists class, operation length, and wound class. There was a 66% reduction in bacterial load in the VLD rooms. No substantial difference was observed in SSI rates between the control and VLD rooms (0.8% vs. 0.8%, p = 0.71). There was no substantial difference in SSI rates by specialty. After adjusting for covariates, VLD was not independently associated with SSI rate. Conclusion: VLD effectively reduced overall operating room bacterial burden; however, this did not result in a substantial reduction in SSI rates. The cause of SSIs is multi-factorial and may be influenced more by patient and technical factors than overall operating room bacterial burden.