**1. Introduction**

140 Atopic Dermatitis – Disease Etiology and Clinical Management

Yamamoto A, Serizawa S, Ito M, Sato Y. 1991, Stratum corneum lipid abnormalities in atopic

Yasueda H, Hashida-Okado T, Saito A, Uchida K, Kuroda M, Onishi Y, Takahashi K,

Zargari A, Midgley G, Bäck O, Johansson SG, Scheynius A. 2003, IgE-reactivity to seven

Zhang E, Tanaka T, Tajima M, Tsuboi R, Nishikawa A, Sugita T. 2011, Characterization of the

Yamaguchi H, Takesako K, Akiyama K. 1998. Identification and cloning of two novel allergens from the lipophilic yeast, *Malassezia furfur*. Biochem Biophys Res

skin fungal microbiota in patients with atopic dermatitis and healthy subjects. *Microbiol Immunol* Jun 24. doi: 10.1111/j.1348-0421.2011.00364.x. [Epub ahead of print]

dermatitis. *Arch Dermatol Res.* 283, 219-223.

*Malassezia* species. *Allergy* 58, 306-311.

Commun. 248, 240-244.

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.
