Initial Evidence of Distinguishable Bacterial and Fungal Dysbiosis in the Skin of Patients with Atopic Dermatitis or Netherton Syndrome.

Atopic dermatitis (AD) is an inflammatory skin disease in which epidermal barrier impairment, often owing to FLG null mutations, precedes immune hyperresponsiveness. Ichthyosis vulgaris is characterized by FLG null mutations and noninflamed dry skin. Netherton syndrome (NS), caused by SPINK5 null mutations, is characterized by generalized erythroderma with scaling and atopic manifestations. The goal of this work was to evaluate associations between specific skin disease features, such as ichthyotic and/or atopic manifestations, and the skin bacterial and fungal microbiota. Taxon diversity showed greater variation in the bacterial microbiota than in the fungal microbiota in the skin diseases. The relative abundances of Firmicutes (Staphylococcus) and Actinobacteria (Corynebacterium) were augmented in ichthyosis vulgaris, AD, and NS, whereas those of Proteobacteria/Enhydrobacter and Bacteroidetes were reduced, regardless of body site. Furthermore, proportions of Staphylococcus were correlated with transepidermal water loss and serum IgE levels. Nevertheless, the skin of patients with low to mild AD was overcolonized with Staphylococcus epidermidis and not with Staphylococcus aureus. Ascomycota were increased in both AD and NS, but from expansion of different fungal species. Finally, the expansion of pathologic bacteria in AD and NS might be supported by surrounding fungi. Thus, distinguishable bacterial and fungal skin dysbiosis in AD, NS, and ichthyosis vulgaris emphasizes disease-specific pathomechanisms.