Prevalence of Malassezia species in patients with pityriasis versicolor in Rosario, Argentina.

BACKGROUND Malassezia species are considered opportunistic yeasts of increasing clinical importance. These lipophilic yeasts are associated with various human diseases, especially pityriasis versicolor (PV), a chronic superficial scaling dermatomycosis. AIMS The aim of this study was to isolate, identify and analyze the distribution of the different species of Malassezia in patients with PV in Rosario city (Argentina). METHODS A total of 264 clinical samples were studied. Isolates were identified on the basis of microscopic observation of cells, and physiological properties, such as the presence of catalase, ability to use Tween compounds, splitting of esculin, and morphology, color and precipitate production on chromogenic agar CHROMagar-Malassezia medium (CHROMM). RESULTS The highest prevalence of PV in this study was observed in the 25- to 45-year-old group. No differences were found in the development of PV between sexes. The most affected areas of body were the trunk and face. Malassezia sympodialis (51%) was the most commonly isolated species, followed in frequency by M. globosa (40%), Malassezia furfur (7%), Malassezia obtusa (1%) and Malassezia slooffiae (1%). CONCLUSIONS The success for a correct identification of these yeasts is important to improve our knowledge about their epidemiological role in PV and also to detect the appearance of strains which are resistant to the commonly used antifungal drugs.