Identification of Malassezia species from immunocompetent and immunocompromised patients with seborrheic dermatitis.

BACKGROUND AND OBJECTIVES: Differences in prevalence, clinical and histological manifestations between seborrheic dermatitis (SD) in immunocompetent and immunocompromised patients suggest that these two populations might also differ in a spectrum of isolated Malassezia species. The purpose of our study was to analyse the prevalence of Malassezia species in immunocompromised and non-immunocompromised patients with SD and to examine if the range of isolated yeasts varies between these two study groups.

PATIENTS AND METHODS: Specimens were taken from 50 patients with SD: 30 without any underlying disease and 20 with confirmed immunosuppression. The samples were obtained by scraping the skin surface of the scalp and trunk lesions of all subjects and then incubated on modified Dixon agar. The yeasts isolated were identified by their morphological and physiological properties according to Guillot et al method.

RESULTS: In both groups, the most commonly isolated species from the scalp lesions were Malassenzia restricta and Malassenzia globosa, the later being the most common species isolated from lesional trunk skin. No significant differences were found between immunocompromised and immunocompetent patients from both sampled sites.

CONCLUSIONS: There is no difference in the distribution of Malassezia species isolated from SD lesions between immunocompetent and immunocompromised patients. However, the much higher percentage of positive cultures in immunocompromised patients confirms that impaired cellular immunity may facilitate fungal survival on the skin.