Seborrheic dermatitis (SD) is a common skin condition affecting the scalp and other sebaceous-rich areas. Most recent studies have focused on the microbiota of individuals with SD and healthy controls, suggesting an association of microbial dysbiosis. The variations in the microbiota at lesional and non-lesional sites of SD patients and healthy controls remain unexplored. The present study aimed to characterize the microbiota in SD patients. We conducted a cross-sectional study to analyse microbial composition and diversity of fungi and bacteria on the lesional and non-lesional sites of SD patients (n = 60) and from the scalp of healthy individuals (n = 30) using culture-based methods and high-throughput sequencing (n = 8 each group) of the ITS2 region of fungal rDNA and the V3-V4 region of bacterial 16S rRNA. The culture-based approach revealed a significant association between the combination of 'Malassezia and aerobic bacteria' and lesions in patients, especially in severe cases. Malassezia restricta, Staphylococcus capitis, and S. epidermidis were the most common isolates. Microbiome results revealed lower species richness of both fungal (observed features, P = .0105 and Chao1, P = .0487) and bacterial (observed features, P = .0016 and Chao1, P = .001) communities with higher relative abundance of M. restricta (61%, P < .0001) and Staphylococcus (40%, P < .0001) and Corynebacterium (16%, P < .0001) on lesional sites than on non-lesional sites. A decrease in alpha diversity of both fungal and bacterial flora, on the lesional site compared to the non-lesional site, suggests an association between site-specific dysbiosis and SD.
Gupta et al. (Tue,) studied this question.