Tacrolimus Has Antifungal Activities against Malassezia furfur Isolated from Healthy Adults and Patients with Atopic Dermatitis

Tacrolimus (FK506), a new immunosuppressant used clinically in the prevention of allograft rejection, has been shown to be effective when used topically in atopic dermatitis, especially for face and neck lesions. Because Malassezia furfur, normally found in the seborrhoeic area, has been suggested to be one of the major allergens in atopic dermatitis and a provocative factor for face and neck lesions, the antifungal activity of tacrolimus against M. furfur was investigated. 26 strains of M. furfur were isolated from healthy adults and adult patients with atopic dermatitis. The growth of all the strains was inhibited by 0.5 to 32 mg/L of tacrolimus, whereas cyclosporin showed no such antifungal activity. This inhibition was found to be mediated by the fungicidal effects of tacrolimus. Microscopic examinations of M. furfur on the faces of patients with atopic dermatitis showed markedly diminished numbers of spores after 1 week’s treatment with topical tacrolimus ointment. The antifungal effects of tacrolimus against the causative allergenic yeast, M. furfur, may also be beneficial when treating face and neck atopic dermatitis with tacrolimus ointment.