Comparative Analysis of the Skin Microbiota of Rosacea, Steroid‐Induced Rosacea and Perioral Dermatitis

Rosacea, steroid-induced rosacea, also known as corticosteroid-induced rosacea-like dermatitis, and perioral dermatitis cause erythema, red papules, and pustules on the face. Tetracycline therapy is often effective for these skin diseases, suggesting that skin bacteria may be involved in these pathogeneses. To explore the etiologic significance of skin bacteria, we examined the microbiota of rosacea, steroid-induced rosacea, and perioral dermatitis, as well as healthy participants (n = 50), using swab specimens that were obtained by rubbing the skin surface and vellus hair specimens that were collected from the perioral lesions. Skin microbiota was determined with short-amplicon sequence analysis for 16S rRNA gene (V1-V2 regions). Comparative analysis of the microbiota showed that the bacterial composition in perioral dermatitis cases was clearly different from that of rosacea cases and healthy participants but similar to that of some cases of steroid-induced rosacea. The uncultured Neisseriales bacterium was prevalent in the skin microbiota of some cases of steroid-induced rosacea and perioral dermatitis cases. After antibiotic therapy to steroid-induced rosacea and perioral dermatitis cases, the uncultured Neisseriales bacterium disappeared with improvement of the skin rash. These results indicate that the skin bacteria involving unculturable bacterium in the skin microbiota had a significant impact on steroid-induced rosacea and perioral dermatitis pathogeneses, and that microbiota-targeted treatment may be effective for steroid-induced rosacea and perioral dermatitis.