Resumo

The human skin microbiome is composed of a complex ecosystem of fungi and bacteria. Propionibacterium is one of the most common bacterial genera found in skin. Fungal microbiota includes mostly organisms from Malassezia genus, which have been also associated with skin disorders such as seborrheic dermatitis (SD), specifically the species Malassezia globosa and M. restricta. This study aims to evaluate the variation of M. globosa, M. restricta, and Propionibacterium sp. populations in the scalp microbiota from healthy individuals and patients with SD under treatment with topic antifungal (2% ketoconazole, 1% salicylic acid). Six healthy subjects and six SD patients were studied. Three sets of scalp samples were obtained using sterile cotton swabs, at 1-month intervals (first sampling prior treatment). Quantitative real time PCR was used to detect and to quantify fungal and bacterial organisms using as target 5.8/ITS-2 rDNA and 16S rDNA, respectively. Microbiotas from different samples were compared through PERMANOVA statistical tests. Healthy individuals showed relative stability over the period of time analyzed for both Malassezia and Propionibacterium populations. As expected, M. globosa and M. restricta varied between samples throughout antifungal treatment, although there were differences among subjects. Interestingly, Propionibacterium population also varied in patient samples, suggesting an ecological interaction between fungi and bacteria, in a way that variation in one population might influence the other. All patients showed symptom improvement, although there is no clear relation with a specific species variation. Our results contribute to the understanding of the relationship between fungal and bacterial populations from scalp microbiota in health and in SD patients, as well as their interaction in the scalp environment.