Distribution of Malassezia species in patients with pityriasis versicolor in Turkey

Summary Pityriasis versicolor is a common superficial mycotic disease of the skin which is caused by different species of Malassezia genus. The aim of this study was to contribute to the knowledge of the aetiology of pityriasis versicolor (PV) with a mycological study made according to the new species and additionally, the success of the different sampling techniques, duration and recurrence history of the disease, distribution of infecting strains according to the affected body sites were also investigated. In total, 146 patients with pityriasis versicolor were included in this study. Fungal elements could only be visualized by potassium hydroxide examination in 36.4% of the samples. Specimens obtained by scraping skin surface by a sterile scalpel and/or sterile sticky plaster (OpSite) were inoculated in plates containing modified Dixon's medium. Out of 146 samples, 109 (74.7%) yielded a growth which was considered to be Malassezia spp. in culture. Species level identification of suspicious Malassezia yeasts was made according to their macroscopic and microscopic features, and their physiological characteristics. Among the identified species, Malassezia globosa (65.1%) was the most commonly isolated species, followed by Malassezia obtusa (17.4%). However, four Malassezia isolates could not be identified at species level with conventional methods. While most of the patients suffered their first episode of pityriasis versicolor (76%), back of the trunk was the mostly affected body site (39%). In conclusion, Malassezia globosa was found to be the predominant species in pityriasis versicolor patients in our region, and culture of the specimen is necessary for the epidemiologic purposes.