Antifungal Activities of Tacrolimus and Azole Agents against the Eleven Currently Accepted Malassezia Species

Abstract

The lipophilic yeast Malassezia is an exacerbating factor in atopic dermatitis (AD) and colonizes the skin surface of patients with AD. With the goal of reducing the number of Malassezia cells, we investigated the antifungal activities of a therapeutic agent for AD, tacrolimus, and the azole agents itraconazole and ketoconazole against Malassezia species in vitro. We examined 125 strains of the 11 currently accepted Malassezia species by using the agar dilution method. All strains of the 11 Malassezia species were very susceptible to both azole agents, with MICs ranging from 0.016 to 0.25 g/ml. Tacrolimus had antifungal activities against half of the strains, with MICs ranging from 16 to 32 g/ml. Two of the major cutaneous floras, Malassezia globosa and Malassezia restricta, have several genotypes in the intergenic spacer region of the rRNA gene; the azole agents had slightly higher MICs for specific genotype strains of both microorganisms. A combination of azole agents and tacrolimus had a synergistic effect against Malassezia isolates, based on a fractional inhibitory index of 0.245 to 0.378. Our results provide the basis for testing these agents in future clinical trials to reduce the number of Malassezia cells colonizing the skin surface in patients with AD.Although lipophilic yeasts, Malassezia spp., colonize the skin surface of healthy individuals, they may also cause seborrheic dermatitis (SD), pityriasis (tinea) versicolor, and Malassezia folliculitis and may exacerbate atopic dermatitis (AD) (1). AD is a common chronic inflammatory skin disease. The standard treatment of AD is topical corticosteroids and topical immunomodulating agents, although some patients do not respond to these treatments. Cutaneous microorganisms are considered an exacerbating factor. Although large numbers of lipophilic Malassezia species organisms colonize the skin surfaces of both AD patients and healthy subjects, anti-Malassezia-specific immunoglobulin E antibody is detected only in AD patient sera (14,16,32). This is probably owing to the disrupted barrier function of the skin surface and the effects of scratching on sensitization to the organisms (30). The application of topical antifungal agents to AD patients decreases Malassezia colonization and the severity of eczematous lesions (2), suggesting that Malassezia species play a role in atopic dermatitis. In addition, several candidate Malassezia antigens have been implicated in the pathogenesis of AD (15,19,20,23,34).In 1996, the taxonomy of the genus Malassezia was revised by Guého et al. (8). The authors described seven species (Malassezia furfur, M. globosa, M. obtusa, M. restricta, M. slooffiae, M. sympodialis, and M. pachydermatis). Subsequently, Japanese researchers found another four new species: Malassezia dermatis (25), M. yamatoensis (28), M. japonica (27), and M. nana (11) were isolated from an AD patient, SD patients, a healthy individual, and an animal, respectively, between 2002 and 2004. At present, 11 species have been accepted in this genus. By use of the r...

A Modified Christensen's Urea and CLSI Broth Microdilution Method for Testing Susceptibilities of SixMalasseziaSpecies to Voriconazole, Itraconazole, and Ketoconazole

“…CLSI RPMI 1640 medium (17) 3 to ϳ10 6 CFU/ml (9,12,13,16,20,21). Although our inoculum density was higher than that recommended for other yeasts (ϳ10 3 CFU/ml) (17), it provided suitable growth for all six species between 72 and 96 h. The inoculum preparation procedure yielded reproducible results (Ͼ92%, 0.5 to 6 ϫ 10 5 CFU/ml after dilution); the others had slightly lower (0.2 ϫ 10 5 CFU/ml) or higher (7 ϫ 10 5 CFU/ml) densities (viable colony counts).…”

Depigmented lesions of pityriasis versicolor: A diagnostic dilemma with review of literature

“…However the hypopigmentation may persist even after effective treatment of PV, so tacrolimus is being used to treat the residual hypopigmentation [7]. Besides all the therapies it is advisable to counsel and treat the patient for hyperhydrosis and other predisposing factors.…”

Atopic Dermatitis and Skin Fungal Microorganisms

“…Ketoconazole and itraconazole are highly effective in vitro (Sugita et al 2005, Miranda et al 2007, Sancak et al 2005, Velegraki et al 2004. In a large-scale study using 125 strains of 11 Malassezia species, all of the Malassezia species were highly susceptible to both itraconazole and ketoconazole, with minimum inhibitory concentrations (MICs) ranging from 0.016 to 0.25 mg/ml; approximately 80% of the strains had a MIC of ≤0.03 mg/ml (Sugita et al (2005). This efficacy is not specific to these species, but applies to all members of the genus Malassezia.…”

“…A calcineurin inhibitor, topical tacrolimus, is widely used to treat AD. This compound had antifungal activity against half of the known Malassezia strains, with MICs of 16-32 mg/mL (Sugita et al 2005). The immunosuppressive drugs cyclosporine and tacrolimus target calcineurin and are also toxic to Candida albicans and Cryptococcus neoformans (Cruz et al 2001).…”