Atopic dermatitis (AD) is the most common chronic inflammatory skin disease. Clinical studies have demonstrated a link between staphylococcal skin colonization and the pathogenesis of AD, but the implication of bacterial virulence factors remains largely uncharacterized. Finally, AD is often associated with herpes simplex skin infections. The aim of this project is to investigate the role of staphylococcal toxins in the exacerbation and maintenance of atopic skin inflammation and in the occurrence of infectious complications such as eczema herpeticum.

Inclusion Criteria:

• Patients with moderate AD (SCORAD between 25 and 50) or severe AD (SCORAD> 50)
• Skin lesions in the forearms
• Free subject, without neither guardianship, wardship nor subordination
• Patient with Social Security
• Informed and signed consent by the patient after clear and loyal information on the study

Exclusion Criteria:

• Age < 18 year-old
• Patients with mild AD (SCORAD < 25)
• Patients without skin lesions in the forearms
• Patients treated with dermocorticoid or calcineurin inhibitor for less than two weeks
• Patients under systemic treatment : Methotrexate, Ciclosporin, Mycophenolate Mofetil, Azathioprine, general corticosteroids for less than 4 weeks
• Patients under biological treatment : Dupilumab for less than 5 half-lives
• Patient without Social Security
• Pregnant and nursing women