Identification of Malassezia species isolated from patients with seborrhoeic dermatitis, atopic dermatitis, pityriasis versicolor and normal subjects.

We identified Malassezia species isolated from 42 patients with seborrhoeic dermatitis, 17 patients with atopic dermatitis, 22 patients with pityriasis versicolor, 35 normal subjects and 73 healthy medical students. Regarding the prevalence of Malassezia species in the 35 normal subjects, the frequency of isolation of Malassezia globosa was 22%, M. sympodialis 10% and M. furfur 3%. M. slooffiae, M. pachydermatis, M. restricta and M. obtusa were infrequently isolated from normal skin. Two different species were isolated coincidentally from seven samples. In the patients with atopic dermatitis, M. furfur was isolated more frequently from lesional skin (21%) than non-lesional skin (11%). However, there was no statistical significance. Therefore, this result, by itself, is insufficient to prove that M. furfur should be considered to be an exacerbating factor of atopic dermatitis. In seborrhoeic dermatitis, M. furfur (35%) and M. globosa (22%) were isolated from lesional skin on the face at significantly high rates in comparison with the normal subjects. Therefore, M. furfur and/or M. globosa may be pathogens of seborrhoeic dermatitis. M. globosa was isolated at a frequency of 55% from lesional skin of pityriasis versicolor, while all other species were below 10%. These data suggest that the pathogenic species of pityriasis versicolor is M. globosa.