Investigation on possible resistance of Candida auris to irradiation with UVC (254 nm).

Candida auris is a yeast that is increasingly pathogenic due to increased multiresistance to antimycotics. UV (ultraviolet) radiation is still capable of reducing C. auris and offers possible applications in radiation disinfection of surfaces and air. However, it is unknown whether C. auris could also develop a resistance against UV radiation. For this reason, the extent to which C. auris can develop resistance to UVC radiation (254 nm) over several irradiation cycles is being examined. The yeast is irradiated with a UVC dose of 18.2 mJ/cm 2 per cycle, followed by a recovery phase under dark conditions. This irradiation-recovery process was repeated for 16 consecutive cycles, ensuring that the UVC dose of 18.2 mJ/cm 2 remained constant throughout all cycles. It was observed that the log reduction (a log 1 reduction corresponds to a 90% reduction) decreased with increasing number of cycles. Resistance development against UVC could be presented.