Identification of Malassezia species isolated from some Malassezia associated skin diseases.

BACKGROUND: The genus Malassezia represents the dominant eukaryotic component of the skin microbial flora. There are complex interactions between this commensal and the skin, leading to various Malassezia-caused or Malassezia exacerbated skin conditions. OBJECTIVES: To identify Malassezia species in lesions of patients with pityriasis versicolor (PV), atopic dermatitis (AD), and seborrheic dermatitis (SD), as well as corresponding sites in healthy subjects according to the culture methods used for Malassezia species isolation. METHODS: Scrapings were collected from 80 patients (40 PV, 20 AD, and 20 SD) and 30 healthy subjects. For 10-14 days, specimens were cultured on Dixon's medium and Malt extract agar. Direct microscopic examination with Gram's stain, subculture on Hi chrome agar, Dixon's medium at various temperatures, Tweens assimilation, and hydrolysis of tryptophan were used for the identification of yeast isolates. RESULTS: The isolation frequency of Malassezia species in healthy subjects was 13.3% for M. furfur, 10.0% for M. globosa, and 3.3% for M.sympodialis. In patients with SD, M. furfur was isolated more frequently from scalp lesions (25.0%) and then M. sympodialis (15%) and M. globosa (10%). Malassezia sympodialis was the most prevalent isolated species in AD lesions (20%), followed by M. furfur (10%). Malassezia species isolation was found to be most prevalent in PV lesions, with M. furfur being the most prevalent identified species (52.5 %), followed by unidentified species (20%). CONCLUSIONS: Malassezia species composition was similar in PV, SD, and healthy subjects, with M. furfur being the commonest isolate, while Malassezia sympodialis was the prevalent species isolated in AD lesions. Chrome agar media can be promising for the identification of Malassezia species phenotypically. However, species differentiation has to be complemented by molecular methods.