Quantitative analysis of Malassezia in the scale of patients with psoriasis using a real-time polymerase chain reaction assay

Background It has been suggested that Malassezia is associated with the development of skin lesions in psoriasis because of the response of the scalp lesions in psoriasis to antifungal agents. Malassezia restricta and M. globosa are the two major members of the cutaneous Malassezia flora in patients with psoriasis, although they have not been analysed quantitatively. Objectives This study quantified the two major cutaneous Malassezia species in psoriatic scale from different body sites using a real-time polymerase chain reaction (PCR) assay. Methods Scale samples were collected from lesional and nonlesional skin of 20 Japanese patients with psoriasis and fungal DNA was extracted from the samples directly. All the Malassezia species, including the two major species M. globosa and M. restricta, were quantified with high accuracy, using a real-time PCR assay. Results Colonization by M. restricta was approximately five times higher at all body sites than colonization by M. globosa. Malassezia colonization was significantly lower in patients with hyperlipidaemia than in patients with normolipidaemia. Conclusions Malassezia restricta is the predominant species in psoriatic scale.