Last update:
11-Nov-2004

Eichestedt first connected Malassezia with skin diseases in 1846, since then the debate regarding the name and the pathogenic potential of the yeast has continued. The expansion of the genus in 1996 to include seven species renewed interest in the epidemiological investigation of diseases directly or indirectly connected to the yeast, such as pityriasis versicolor, seborrheic and atopic dermatitis. The resulting data show prevalence of M. globosa in the Mediteranean region with gradual decline in the isolation rate as the population samples are derived from northern European countries. In the Scandinavian region large numbers of M. obtusa are isolated, a species almost never found in the south. Malassezia is implicated in the production of substances which cause pityriasis versicolor but also protect the skin in the hypopigmented lesions from ultraviolet radiation, in an “affectionate” host-parasite relationship. Data regarding the implication of the genus in seborrheic dermatitis are conclusive for an irritating yet non-specific role. Malassezia also plays a part in the pathogenesis of atopic dermatitis and psoriasis, diseases with great impact in the general population. Allergenic proteins implicated in atopic dermatitis with predominant face and neck distribution have been identified and subsequently isolated. Experimental data from a study of psoriasis supports implication of Malassezia in this dermopathy, although further investigative work is necessary. Of paramount importance is the involvement of Malassezia yeasts in systemic disease in immunocompromised patients, mainly in those receiving total parenteral nutrition supplemented with lipids via a central venous catheter. In this subset of patients M. pachydermatis plays an important role as it may cause sepsis in low birth-weight premature infants as either solitary cases or in epidemics.

Key words: Malassezia, Skin disease, Systemic disease.