Antimicrobial blue light against healthcare-related Candida species: in vitro efficacy and following repeated exposure for 30 days.

Antifungal resistance and invasive fungal infections are increasing mainly due to the lack of effective diagnostic methods and therapeutic options. The World Health Organization has formally designated several fungal pathogens as a major public health concern, including Candida spp. Indeed, the presence of fungal pathogens in hospitals represents a reservoir that persists in the areas and equipment surrounding patients. Therefore, the application of disinfection measures is imperative to reduce microbial contamination and disrupt transmission routes.Antimicrobial blue light (aBL) has emerged as a novel disinfection method. The present study evaluated the efficacy of aBL, with a combination of wavelengths of 405 nm and 430 - 470 nm, in inactivating Candida species over 8 h. Furthermore, the most susceptible strain was repeatedly exposed to aBL for 30 days, and its phenotypic characteristics were assessed throughout the experiment.Exposure to aBL has demonstrated to exhibit a dose-dependent antifungal effect across all the Candida species examined. The most tolerant species was C. albicans, followed by C. auris and C. parapsilosis. C. glabrata was the most susceptible species. Despite being repeatedly exposed for 30 days to a dose corresponding to 11% survival, C. glabrata demonstrated no alterations in its response to aBL, nor did it exhibit any change in antifungal susceptibility or in its capacity to form biofilm.In summary, the evidence suggests that aBL disinfection may be a safe approach for Candida decontamination, as it neither induces photo-tolerance in the most susceptible C. glabrata strain nor compromises its phenotypic characteristics.