Effects of Treatments on Atopic Dermatitis

Background: \- Atopic dermatitis, or eczema, is a chronic skin disorder. Patients sometimes have infections with S. aureus bacteria. Researchers want to study how eczema treatments affect the number and the type of bacteria on the skin. Objectives: \- To study the effect of eczema treatments on skin bacteria. Eligibility: * Individuals between 2 and 25 years of age who have moderate to severe atopic dermatitis. * Healthy volunteers between 18 and 40 years of age with no history of eczema. Design: * Participants will be screened with a physical exam and medical history. Research samples will be collected. Skin biopsies may also be performed. * All participants will be assigned to one of several study groups. * Healthy volunteers must not have taken antibiotics in the year before the start of the study. * All participants will have regular study visits during their 1-year participation. More research samples will be collected at these visits. * Healthy volunteers may be asked to come in for a one-time follow up after the 1 year mark.