Dictionary of Allergies .. Atopic dermatitis and yeasts

Saprofytic yeasts Pityrosporum ovale and Candida albicans induce specific IgE production in patients with atopic dermatitis (AD), especially in patients with head and neck shoulder (HNS) distribution of the dermatitisor generalized forms of AD. It has been demonstrated that saprophytic yeasts may induce immunoresponses  which  may switch the Th2 response towards Th1 and vice versa[1]. Malassezia y lipophilic easts not only cause the well known pityriasis versicolor and folliculitis, but also play an important role in other skin diseases, including seborrheic dermatitis and atopic dermatitis2..

The presence of Malassezia yeasts may be confirmed by direct microscopic examination and cultures of skin scrapings. Specific IgE antibodies to Malassezia sp., skin prick tests, atopy patch tests indicate that these yeasts may be an important allergen especially in patients with AD localized on the head and neck. During exacerbations of the AD, supplementary treatment with proper antifungal agents has been shown to be of great value[2].

References

Kalimo K et al: Yeasts and atopic dermatitis. The annual Meeting of the European academy  of Allergology and Clinical Immunology. Brussels, Belgium, July 3-7, 1999. Allergy suppl. 52:54:25, 1999.

2. Difonzo EM, Faggi E. Skin diseases associated with Malassezia species in humans. Clinical features and diagnostic criteria. Parassitologia. 2008 Jun;50(1-2):69-71.

2. Bielńska-Warezak D, Nowicki R. The role of the yeasts Malassezia sp. in etiopathology of atopic dermatitis. Pol Merkur Lekarski. 2005 Feb;18(104):241-4.