Ｍａｌａｓｓｅｚｉａと脂漏性皮膚炎・アトピー性皮膚炎

Abstract

Malassezia species, organisms normally colonizing the skin surface, are thought to play a role as either the cause or an exacerbating factor in a number of skin conditions, including pityriasis versicolor, Malassezia folliculitis, seborrheic dermatitis (SD) and atopic dermatitis (AD). Using a non-cultural PCR method, we analyzed Malassezia spp. extracted from the skin surface of SD and AD patients. The species most commonly detected in both patient groups were M. globosa and M. restricta, and the number of Malassezia spp. In these patients was higher than in healthy subjects. After a topical application of 2% ketoconazole cream, changes in the population of Malassezia spp. in 20 intractable cases of AD were recorded. The addition of the 2% ketoconazole cream to the standard topical treatments was found to have reduced the Malassezia spp. population by 90%, and showed a clinical efficacy rate of 70%. Furthermore, a combination of azole agents and tacrolimus produced a synergistic anti-fungal effect against Malassezia spp. in vitro. A clinical trial using this drug combination conducted on the face and neck of patients with intractable AD showed a 66.6% efficacy rate in both the reduction of the flora and in clinical improvement. From these results it was evident that Malassezia is one of the factors exacerbating AD, and that removal of the organism results in an improvement in the clinical condition of the patient.