ABSTRACT
Although the clinical conditions pityriasis versicolor, seborrheic dermatitis, atopic dermatitis, and psoriasis are quite different, the cutaneous Malassezia microbiota in patients with
73.1 Introduction ..................................................................................................................................................................... 643 73.1.1 Taxonomy ............................................................................................................................................................ 643 73.1.2 Epidemiology ....................................................................................................................................................... 643 73.1.3 Immunological Aspects ....................................................................................................................................... 645 73.1.4 Diagnosis ............................................................................................................................................................. 645
73.1.4.1 Conventional Techniques ...................................................................................................................... 645 73.1.4.2 Molecular Techniques ........................................................................................................................... 645
73.2 Method ............................................................................................................................................................................. 647 73.2.1 Sample Preparation .............................................................................................................................................. 647 73.2.2 Detection Procedures ........................................................................................................................................... 647
73.2.2.1 Identi–cation by PCR and Sequencing ................................................................................................. 647 73.2.2.2 Nested PCR Detection .......................................................................................................................... 647 73.2.2.3 Real-Time PCR Quantitation ................................................................................................................ 649
73.3 Conclusion ....................................................................................................................................................................... 649 References ................................................................................................................................................................................. 650
these skin diseases is almost identical [8-12]. Pityriasis versicolor develops on the trunk and upper arms of people in their 20s and 30s, occurring more often during the summer than the winter, whereas seborrheic dermatitis develops in areas of the body that are rich in sebaceous glands, such as the face, scalp, and upper trunk. Atopic dermatitis is a chronic disease involving cycles of remission and deterioration and is characterized by hypersensitivity to dry skin. Psoriasis is a multifactorial skin disease with a strong genetic component, including several genes encoding proteins involved in epidermal differentiation and immune, in¼ammatory, and pathogen responses. Of the nine human-associated Malassezia species, both M. globosa and M. restricta are commonly detected from almost all patients, whereas the other species are found in fewer than 60% of cases (Table 73.1). Quantitative analysis gives additional interesting results. Although the Malassezia microbiota is similar regardless of skin disease, the ratio of M. globosa to M. restricta differs according to disease (Figure 73.1). In seborrheic dermatitis, M. restricta predominates over M. globosa, whereas M. globosa is the predominant species in pityriasis versicolor. The colonization level of
M. restricta is twice that of M. globosa in atopic dermatitis and psoriasis. Therefore, the Malassezia microbiota is identical qualitatively but signi–cantly different quantitatively in each skin disease.
