The role of microorganisms in atopic dermatitis.

The course of atopic dermatitis is widely determined by environmental factors such as physical or psychogenic stress and reactions to allergens or microorganisms. The latter include bacteria, viruses and fungi, especially Staphylococcus auerus, Herpes simplex virus (HSV), and Pityrosporum orbiculare. In childhood, Impetigo around the big joints is frequently seen, while the characteristic reaction to S. auerus in the young adults is pruritic pustules on the extremities or an exacerbation of the eczema to an exudative dermatitis. Similarily, P. orbiculare may induce a flare-up of the eczema of the head and neck, while HSV may cause a true wide-spread infection known as eczema herpeticum. An immunological disorder, a fragile skin, and special properties of the microorganism may account for the altered response to infection or severe colonization in the patient with atopic eczema. During exacerbations of the eczema, supplementary treatment with proper antimicrobial agents has been shown to be of great value.