Summary/Abstract Atopic dermatitis (AD) is a common inflammatory skin disease. Recent observations strongly suggest that the abnormal microbiome present on the skin of subjects with AD is a major factor that influences the severity and chronic nature of this disorder. In particular, Staphylococcus aureus promotes epidermal barrier dysfunction and exacerbates the local and systemic immune response. In healthy subjects, beneficial members of the skin microbiome act to limit the growth of Staphylococcus aureus but these beneficial bacterial strains are missing on adults with AD. This project seeks to understand why adults with AD lack beneficial bacterial strains by study of the survival of a prototype strain of Staphylococcus hominis on AD skin. Interventions to improve its survival will be tested, and application in the pediatric AD population will be evaluated. Overall, successful completion of the proposed aims of this ADRN Clinical Research Center will advance understanding of AD and provide essential information to permit development of an innovative new therapeutic approach based on targeted microbiome therapy.