Comparison of the skin microbiota in acne and rosacea.

Acne and rosacea, despite their similar clinical presentations, follow distinct clinical courses, suggesting that fundamental differences exist in their pathophysiology. We performed a case-control study profiling the skin microbiota in rosacea and acne patients compared to matched controls. Nineteen rosacea and eight acne patients were matched to controls by age ± 5 years, sex and race. DNA was extracted from facial skin swabs. The V3V4 region of the bacterial 16S rRNA gene was sequenced using Illumina MiSeq and analysed using QIIME/Metastats 2.0 software. The mean relative abundance of Cutibacterium acnes in rosacea with inflammatory papules and pustules (20.454% ±16.943%) was more similar to that of acne (19.055% ±15.469%) than that of rosacea without inflammatory papules and pustules (30.419% ±21.862%). C acnes (P = .048) and Serratia marcescens (P = .038) were significantly enriched in individuals with rosacea compared to acne. Investigating the differences between the skin microbiota in acne and rosacea can provide important clues towards understanding the disease progression in each condition.