In vitro susceptibility of the seven Malassezia species to ketoconazole, voriconazole, itraconazole and terbinafine

Abstract

Fifty-five strains, either authentic or ex-type, of seven Malassezia species were investigated for in vitro susceptibility to various concentrations (0.03-64.0 μg/mL) of three azole drugs, ketoconazole, voriconazole and itraconazole, as well as the allylamine terbinafine, using the agar dilution method. All strains of the seven Malassezia species were susceptible to the three azole drugs at low concentrations. M. furfur, M. sympodialis, M. slooffiae, M. pachydermatis, M. globosa, M. obtusa and M. restricta were most sensitive to ketoconazole and itraconazole, with minimum inhibitory concentrations (MICs) ranging from ≤ 0.03 to 0.125 μg/mL. The recently introduced antifungal, voriconazole, was also very effective, with MIC80 values ≤ 0.03 μg/mL for 80% of strains. MICs of terbinafine against the seven Malassezia species ranged from ≤ 0.03 to 64.0 μg/mL. There were variations in susceptibility of the seven Malassezia species to ketoconazole, voriconazole, itraconazole and terbinafine. Strains of M. furfur, M. globosa and M. obtusa were more tolerant to terbinafine than the remaining Malassezia species; M. sympodialis was highly susceptible. M. furfur strains tested with terbinafine ranged from highly susceptible to relatively resistant. Correct identification of Malassezia species could facilitate selection of appropriate antifungal therapy.