Antifungal activities of fluconazole and ketoconazole agents against Malassezia species

Background and Malassezia, a yeast-like fungus found in normal skin flora is known to be associated with various skin diseases, along with systemic infections. Our aim was to determine the in -vitro susceptibility of Malassezia spp. to ketoconazole and fluconazole. In this study, we identified 99 Malassezia isolates from patients with pityriasis vesicular by morphological and biochemical criteria. In vitro susceptibility testing was in macro-broth dilutions, conducted based on the National Committee for Clinical Laboratory Standards (NCCLS) M27-A proposed standard. The results were analyzed statistically by Mann-Whitney. The Malassezia isolates were identified as M. globosa (42), M. furfur (39), M. obtusa (10), M. sympodialis (6), and M.slooffiae (2). The rate of MFC of ketoconazole against Malassezia spp. was 0.06-2 µg/ml, while the MFC of fluconazole against Malassezia spp. was 2-64 µg/ml. The minimal inhibitory concentration (MIC90) of ketoconazole against Malassezia spp. was 0.03-1 µg/ml, while the minimal inhibitory concentration (MIC90) of fluconazole against Malassezia spp. was 0.5-32 µg/ml. Although fluconazole can be an effective treatment option for pityriasis versicolor, in our study, fluconazole MICs were higher than ketoclonazole.