Role of Malassezia yeast (Pityrosporum) in seborrhoeic dermatitis (SD).

Abstract

The objective of this study was to find out the prevalence of Pityrosporum species in the patients with seborrheic dermatitis (SD) and compare the colonization rate with normal healthy individuals. Comparative study. Dermatology Department, Military Hospital and Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi from 01 March 1996 to 28 February 1997. Fifty patients with clinically diagnosed seborrheic dermatitis were included in this study. Fifty normal healthy individual with matched age and gender were included as control subjects. Three samples from each effected sites were taken from 2 cm2 area. Identical sites in control subjects were also sampled. These samples were examined under the microscope after treating with 10% potassium hydroxide and staining with parker blue black ink for the presence of Pityrosporum yeast cells. The specimen were also inoculated in special lipid enriched media, incubated at 37 degrees C for 4-6 days. Out of 50 patients, Pityrosporum yeast cells were seen microscopically in 37 (74%), and the cultures were positive in 43 (86%). Among the normal individuals yeast cells were seen microscopically in 23 (46%) and the cultures were positive in 22 (44%). The colonization rate of Pityrosporum species was higher in the seborrheic dermatitis patients. It might be playing a causative role in the aetiology of this disease.