The basidiomycetous yeasts Cryptococcus diffluens and C. liquefaciens colonize the skin of patients with atopic dermatitis

Our previous research showed that lipophilic yeasts, Malassezia species, colonize the skin of patients with atopic dermatitis (AD) at a high frequency. In this study, we found that two basidiomycetous yeasts, Cryptococcus diffluens and C. liquefaciens, colonize the skin significantly more frequently in AD patients than in healthy subjects. Transparent dressings were applied to the skin of 36 AD patients and 30 healthy subjects and then transferred onto Sabouraud dextrose agar. Colonies recovered from the medium were identified by DNA sequence analysis of internal transcribed spacer regions and the D1/D2 26S rRNA gene. C. diffluens and C. liquefaciens were isolated from 42% (15/36) and 33% (12/36) of AD patients and from 20% (6/30) and 20% (6/30) of healthy subjects, respectively. In addition, fungal DNA was extracted directly from the dressings and amplified in a specific nested PCR assay. C. diffluens and C. liquefaciens DNA were detected in dressings from 97% (35/36) and 86% (31/36) of the AD patients and 47% (14/30) and 37% (11/30) of the healthy subjects, respectively. These findings show that Malassezia spp. are not the only yeasts that colonize the skin of AD patients; Cryptococcus spp. also are present in a high proportion of patients. The role of these microorganisms in AD is as yet unknown, but the current findings, in combination with previous results, indicate that C. diffluens, C. liquefaciens, M. globosa, and M. restricta together colonize the skin surface of AD patients at a high frequency.