Atopic dermatitis (AD), a heterogeneous, chronic inflammatory skin disease, is associated with skin microbiome dysbiosis and features decreased bacterial diversity and increased relative abundance of Staphylococcus aureus (S. aureus).

The present study characterized the poorly understood link between the skin microbiome and patients′ demographic and clinical cofactors concerning AD severity.

It investigated the skin microbiome in 48 adult moderate-to-severe AD patients using next-generation deep sequencing (16S rRNA gene, V1-V3 region) followed by denoising (DADA2) to acquire amplicon sequence variant (ASV) composition.

The study observed-

• In lesional skin, AD severity is associated with S. aureus relative abundance and slightly better with the microbiome diversity measure Evenness, but not Richness.
• The association of AD severity with microbiome diversity, including Shannon, Evenness, or S. aureus relative abundance, and with patients′ IgE levels, race, age, and sex.
• The lesional model described 62% of the variation in AD severity, and the non-lesional model 50% of the variation.

The present study identified the frequently reported "reduced diversity" of the AD-related skin microbiome to reduced Evenness, which is mainly driven by S. aureus relative abundance rather than a reduced microbiome Richness. Discovering relationships between AD severity, the skin microbiome, and the patient′s cofactors is crucial for developing new personalized AD treatments, especially those targeting the AD microbiome.

J Eur Acad Dermatol Venereol. 2022 Nov 25. doi: 10.1111/jdv.18776. Epub ahead of print. PMID: 36433676.