The Efficacy of Ultraviolet Irradiation on Trichophyton Species Isolated From Nails

BACKGROUND: The treatment of onychomycosis is a challenge and infections are typically more severe and difficult to treat in toenails than in fingernails. OBJECTIVES: The current study aimed to investigate the fungicidal effect of ultraviolet radiation on the growth of dermatophytes isolated from nails. PATIENTS AND METHODS: Samples from patients with clinical manifestations of onychomycosis were inoculated onto Sabouraud dextrose agar and incubated at 30°C for 14 days. Isolated species were identified by specific laboratory examinations; UV-A, UV-B, and UV-C light were used to irradiate two strains of Trichophyton mentagrophytes and T. rubrum. Colony count, size and growth rate of the isolated fungi were evaluated under laboratory conditions. RESULTS: Trichophyton rubrum type 1 was less sensitive to UV-A and UV-C, and more sensitive to UV-B than type 2. T. mentagrophytes type 2 was slightly responsive to UV-A therapy, although no decrease in colony count was observed. Increased doses of UV-B and UV-C irradiation decreased the counts. The effect of radiation on colony size was dependent on the dose and type of irradiation. CONCLUSIONS: UV-A, UV-B, and UV-C light seem to be effective in decreasing colony growth of the most prevalent fungi, which caused onychomycosis in the current study samples. Further studies are needed to determine the efficacy of ultraviolet light therapy, identify possible side effects, and establish appropriate dosages for the antifungal effect of this therapy.