Identification of Malassezia Species in Patients with Pityriasis Versicolor Submitted to the Razi Hospital in Tehran.

Lipophilic yeast of the genus Malassezia (Pityrosporum) belongs to the normal flora of human skin and many warm-blooded animals. These fungi can produce a diverse range of diseases that the best known and most frequent of them is pityriasis versicolor, a chronic recurrent skin disease occurring primarily in tropical regions. The genus Malassezia has been recently enlarged to include seven distinct species. Very little information has been documented about identifying Malassezia species in Iran. This survey was undertaken to present a practical approach for differentiation of all Malassezia yeasts isolated from clinical materials of patients with pityriasis versicolor for the first time in Iran. The presence of the disease was confirmed on the basis of the observation of budding yeast cells and short curved hyphae in skin specimens by direct microscopy. Malassezia yeasts were isolated after culturing the samples on modified Dixon (mDixon) agar. A combination of different characteristics includes yeast cell morphology, ability to growth on sabouraud dextrose agar, catalase test and ability to utilize individual Tweens (20, 40, 60, 80) were used for identification of species. In general, 138 patients with pityriasis versicolor includes 52.2% male and 47.8% female were identified. Direct microscopy and culture results were positive in 94.4% and 63% of the patients, respectively. Totally, 91 isolates of Malassezia belonging to four different species, M. globosa (66 isolates), M. furfur (18 isolates), M. obtusa (5 isolates) and M. sympodialis (2 isolates) were identified.