Quantitative skin cultures of Pityrosporum yeasts in patients seropositive for the human immunodeficiency virus with and without seborrheic dermatitis

Abstract

Previous studies have suggested that Pityrosporum yeasts may be important in the pathogenesis of seborrheic dermatitis (SD). SD occurs more frequently and has a different clinical appearance in patients who are human immunodeficiency virus (HIV)-seropositive than in HIV-seronegative patients. Our purpose was to investigate the role of Pityrosporum yeasts in the pathogenesis of seborrheic dermatitis in HIV-seropositive patients. Twenty-eight HIV-seropositive patients, including seven patients with SD and 21 without SD, and 20 HIV-seronegative patients with SD (n = 10) and without SD (n = 10) were investigated. Quantitative Pityrosporum cultures were taken from the face, chest, and back. None or only a small amount of Pityrosporum yeasts were cultured from SD lesions and SD predilection sites in HIV-seropositive patients. From the SD lesions in the HIV-seronegative control group large amounts of Pityrosporum yeasts were cultured. The results of this and other studies suggest that Pityrosporum yeasts play no role in SD in HIV-seropositive patients and that SD in these patients is a distinct entity to be separated from "classical" SD in HIV-seronegative patients.