الفهرس 
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Abstract
Seborrheic dermatitis is a chronic relapsing skin disorder characterized by erythema and scaling. SD causes occasional pruritus, dandruff, and yellow, greasy scaling along the hairline and on the face and in certain body sites rich in sebaceous glands. It affects all age groups and has two peaks of flare, the neonatal period and during puberty when increased secretion of sebum due to hormonal change.
The pathogenesis of SD is unclear, but its activity has been linked to the number of Malassezia yeasts present on the skin. SD may be more common and more severe among patients with neurologic disorders (especially Parkinson disease) or HIV/AIDS. Very rarely, the dermatitis becomes generalized.
Mallassezia species isolated from human skin, was discovered a century ago and was revised on the basis of morphological, physiological and rRNA studies and 18 lipid dependent species were discovered. Many reports have shown that the skin of healthy animals, in addition to human skin may have also been colonized by the lipid-dependent species as M. furfur, M. globosa, M.sympodialis, and M.obtusa and other species were found also in cattle and goats.
This study aimed to identify different Malassezia species in SD patients of different age groups and both sexes by using specific fast growth media chrom agar.
This descriptive study included 49 patients diagnosed clinically with SD attending Ain Shams university hospital, a skin scraping was taken by sterile scalpel from different lesional areas and treated with KOH then cultured on non specific media (Sabarouds and Dixon’s media) after that sub cultured on rapid growing chrom agar to detect Malassezia species.
Despite its simplicity, false positive and false negative results from KOH examination occur in clinical practice, which may be caused by incorrect sampling of the lesion, or inexperience in interpretation
KOH results were 85.71 % positive, 10.20% negative and 4.08% were obscured.
Culture was done for all samples as there was false negative KOH results, scales cultured on Dixon media after incubation time of a week Malassezia results transferred to other media which is fast growing media chrOM agar.
53.06%, of samples showed Malassezia growth on Dixon’s agar others were bacterial growth, mixed growth and one sample showed no growth.
Culture on Chorom agar showed M.furfur (57.6%), M.sympodialis (34.6%) and M.globosa (7.7%) of positive cultured samples.
M.furfur predominate in males while M.sympodialis predominate in females and M.globosa was equal in both sexes. There were no significant correlation between Malassezia species and sex.
M.furfur predominate in the scalp lesions, M.sympodialis predominate in postauricular areas, however there was no significant correlation.
There was no significant correlation between Malassezia species and age or site of lesion.