The purpose of this multi-center, clinical registry study is to determine genetic markers associated with susceptibility of AD patients to infections and to also serve as a potential participant database for future studies.

People with atopic dermatitis (AD), also known as eczema, experience hot, dry, scaly skin with severe itching. In addition, people with AD are prone to skin infections and inflammation. Little is known about the causes of AD or why people with AD are more prone to infections. The purpose of this multi-center, clinical registry study is to determine genetic markers associated with susceptibility of AD patients to infections and to also serve as a potential participant database for future studies.

Study procedures will usually be completed in one visit to the clinic; however, participants may need to return for one or more additional visits to provide blood and skin swabs if they do not meet sampling criteria at the initial Screening Visit. A subset of participants from National Jewish Health may be asked to return to clinic for 2 additional visits approximately 7 and 14 days after the original sample collection for collection of skin swabs for assessment of antimicrobial activity. All participants may also be asked to return for an Unscheduled Visit to provide additional blood and/or skin swabs. Atopic Dermatitis with previous or current Eczema Herpeticum (ADEH+), Atopic Dermatitis with previous or current Eczema Vaccinatum (ADEV+) and Methicillin-Resistant S. Aureus (MRSA+) participants will be contacted every 6 months for the duration of the study.

Recruitment emphasis will include Non-Hispanic Caucasian, Non-Hispanic African American, and Mexican American since these constitute the three largest racial/ethnic populations according to the U.S. Census Bureau 2009 data; however, no racial/ethnic groups will be excluded. Our scientific rationale for targeting these three racial/ethnic groups is to ensure that we are able to recruit sufficient numbers of participants in each group to perform meaningful tests for genetic association.

Inclusion Criteria:

Participants who meet all of the following criteria are eligible for enrollment. Participants may be reassessed if not initially eligible.

• ADEH+ and Non-atopic males and females ages 8 months to 80 years, inclusive, at the time of Enrollment, and ADEH- males and females ages 3 years to 80 years, inclusive, at the time of Enrollment.
• Who are willing to sign the informed consent form or whose parent or legal guardian is willing to sign the informed consent form (age appropriate) prior to initiation of any study procedures.
• Who are willing to sign the assent form, if age appropriate.
• Who meet criteria for one of the diagnostic groups (ADEH-Staph+, ADEH-Staph-, ADEH+, ADEV+, Non-atopic) as defined in the ADRN Standard Diagnostic Criteria and the Staphylococcus aureus Colonization Criteria.

Exclusion Criteria:

Participants who meet any of the following criteria are not eligible for enrollment.

• Who have an active systemic malignancy; uncomplicated non-melanoma skin cancer and melanoma in situ with documentation of complete excision are not exclusionary.
• Who have any skin disease other than AD that might compromise the stratum corneum barrier (e.g., bullous diseases, psoriasis, cutaneous T cell lymphoma [also called Mycosis Fungoides or Sezary syndrome], dermatitis herpetiformis, Hailey-Hailey, or Darier's disease).
• Who have a history of systemic immunological illness (e.g., immunodeficiency disorders such as human immunodeficiency virus [HIV] or lupus erythematosus) other than the condition being studied.
• Who have a first degree relative already enrolled in the study.
• Who are determined not to be eligible in the opinion of the Investigator.

A minimum of 1100 ADEH-Staph+ participants and a minimum of 1100 ADEH-Staph- participants 3-80 years of age will be enrolled. In addition, ADEH+, ADEV+, and Non-atopic participants 8 months to 80 years of age will be enrolled.

It is unknown whether Staph colonization status will change as younger participants get older. For this reason, the lower age limit for inclusion of ADEH- participants is 3 years rather than 8 months to ensure that characterization of their Staph+ vs. Staph- state is more accurate