What is the role of microbial agents in the etiology of pediatric atopic dermatitis (AD)?

Updated: Jun 03, 2020
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Answer

Microbial agents (eg, S aureus, Pityrosporum yeasts, Candida organisms, Trichophyton dermatophytes) act in two different ways to promote the flares of atopic dermatitis. The microorganisms directly invade the skin, creating local injury and inflammation, and they induce a systemic allergic response to specific antigens, causing a rise in serum IgE and enhanced activity of the immune system. Anti-IgE drugs diminish pediatric atopic dermatitis severity. [11]

Nearly all patients with atopic dermatitis are colonized by S aureus on lesional skin. More than half of patients with atopic dermatitis are colonized by S aureus strains capable of producing superantigens. These patients can develop superantigen-specific IgE antibodies that activate inflammatory cells in the skin. Staphylococcal enterotoxin B is a superantigen known to upregulate IL-31 expression in skin. IL-31 has been shown to induce pruritus and skin lesions resembling atopic dermatitis in mice. [2] In addition, methicillin-resistant S aureus strains with reduced susceptibility to vancomycin are increasing worldwide and have been documented in atopic children. [12]


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