Staphylococcus Aureus-Culture Positivity Observed In Adults With Atopic Dermatitis Is Most Indicative Of An Increased Absolute and Relative Abundance Of S. Aureus and Not Reduced Biodiversity

RATIONALE: Subjects with atopic dermatitis (AD) are susceptible to Staphylococcus aureus (S. aureus; SA) colonization. The Atopic Dermatitis Research Network performed a cross-sectional AD study to better characterize subjects with (ADSA+) and without (ADSA-) skin SA-culture positivity.

METHODS: We utilized four different methods to quantify and characterize SA from nonlesional (NL) and lesional (L) swabs of 48 ADSA+ and 44 ADSA- adults. We obtained: SA-culture positivity from swabs cultured for 48hrs on non-selective blood agar, SA abundance determined by qPCR of the SA-specific thermonuclease gene, V1-V3 16S rRNA analysis of gDNA, and metagenome analysis of (n=22) matched 16S NL and L samples from ADSA+ and ADSA-.

RESULTS: SA abundance was highly variable with greater mean expression in ADSA+ than ADSA- (p<0.02; at NL or L site) but no difference between NL and L sites within each group. Microbiome analysis revealed similar levels of taxa diversity (by Chao1, Shannon’s diversity, phylogenetic diversity whole tree or Strong’s dominance index) between ADSA+ and ADSA-. Nevertheless, SA distribution was much greater in ADSA+ than ADSA- skin sites (p<0.0001). Preliminary metagenome analysis identified three viral genera, beta- and gamma-papillomavirus and Molluscipoxvirus, among the top 10 most abundant taxa in 59% (n=13) of AD subjects.

CONCLUSIONS: Our cross-sectional study demonstrates that adult AD subjects with (ADSA+) or without S. aureus-culture positivity (ADSA-) differ most notably in their absolute and relative quantity of S. aureus whereas microbial biodiversity was not different. Additionally, we found that 3 viral genera were remarkably common in the skin of our AD subjects.