Fungus as an Exacerbating Factor of Atopic Dermatitis, and Control of Fungi for the Remission of the Disease

Abstract

Atopic dermatitis (AD) is a common, chronic fluctuating skin disease with prevalence in children (Williams, 2000; Williams & Wüthrich, 2000). The disease is an inflammatory skin disorder characterized by itching, and chronically relapsing course. Moreover, it also produces vulnerablity to surface infections caused by pathogenic bacteria, fungi and viruses. The most common skin infections in AD patients are caused by Staphylococcus aureus and herpes simplex virus (Ong & Leung, 2010). S. aureus is frequently detected in AD patients (Abeck & Mempel, 1998; Katsarou & Armenaka, 2011) and becomes an aggravating factor. In addition, toxins, such as staphylococcal enterotoxins and toxic shock syndrome toxin-1 (McFadden et al., 1993; Bunikowski et al., 1999), generated from S. aureus may act as superantigens (Herz et al., 1999; Niebuhr et al., 2011; Yeung et al., 2011). In AD patients, viral infection is most often caused by herpes simplex virus (HSV) (Wollenberg et al., 2003). Eczema herpeticum is a potentially life-threatening disseminated HSV type 1 or type 2 infection that occurs in 10% to 20% of AD patients (Peng et al., 2007). However, not only bacteria and viruses but also fungi, such as Malassezia species and Candida species, may play an important role as aggravation factors in AD patients. It has been reported that antifungal therapy is beneficial in the treatment of some AD patients (Bäck et al. 1995; Svejgaard et al. 2004; Broberg et al. 1995; Mayser et al., 2006). In addition, several candidate Malassezia antigens have been implicated in the pathogenesis of AD. In this chapter, the involvement of fungi in the pathogenesis of AD is discussed.