Molecular Analysis of Malassezia Microflora on the Skin of the Patients with Atopic Dermatitis

Abstract

Background:The yeasts of the genus Malassezia are members of the normal flora on human skin and they are found in 75∼80% of healthy adults. Since its association with various skin disorders have been known, there have been a growing number of reports that have implicated Malassezia yeast in atopic dermatitis (AD). Objective: The aim of the present study is to isolate the various Malassezia species from AD patients by using 26S rDNA (ribosomal Deoxyribonucleic acid) PCR-RFLP and to investigate the relationship between a positive Malassezia culture and the severity of AD. Methods: Cultures for Malassezia yeasts were taken from the scalp, cheek, chest, arm and thigh of 60 patients with atopic dermatitis. We used a rapid and accurate molecular biological method 26S rDNA PCR-RFLP, and this method can overcome the limits of the morphological and biochemical methods. Results: Positive Malassezia growth was noted on 51.7% of the patients with atopic dermatitis by 26S rDNA PCR-RFLP analysis. The overall dominant species was M. sympodialis (16.3%). M. restricta was the most common species on the scalp (30.0%) and cheek (16.7%). M. sympodialis (28.3%) was the most common species on the chest. The positive culture rate was the highest for the 11 ∼20 age group (59.0%) and the scalp showed the highest rate at 66.7%. There was no significant relationship between the Malassezia species and SCORing for Atopic Dermatitis (SCORAD). Conclusion: The fact that the cultured species was different for the atopic dermatitis lesion skin from that of the normal skin may be due to the disrupted skin barrier function and sensitization of the organism induced by scratching in the AD lesion-skin. But there was no relationship between the Malassezia type and the severity score. The severity score is thought to depend not on the type, but also on the quantity of the yeast.

Cutaneous yeast microflora in patients with atopic dermatitis

“…These two yeast species, together with R. rubra, could be assumed to be transient microorganisms; however, the rather high incidence rate does not foreclose the possible importance in AD clinical evaluation of these microorganisms. Interestingly, the mycological colonization rate in adult patients with AD is similar in all studies, independently of isolated fungal species and geographical distribution, with an approximate frequency of 50% [13,36].…”

“…Malassezia has been isolated in 46%-100% of patients with atopic dermatitis and in 75%-80% of healthy adults worldwide; M. sympodialis, M. globosa, M. furfur and M. restricta were the most commonly isolated Malassezia species [10,12,13,36]. There are some reports that C. albicans has been cultured more frequently from the gastrointestinal tract in patients with AD than in that of healthy controls [37].…”

“…The yeast Malassezia is considered to be an important factor in the course of AD clinical history. Sensitization to the yeast can be detected in approximately 50% of adult patients [10][11][12][13]. However, if majority of healthy individuals have IgG antibodies to Malassezia, 30%-80% of AD patients show IgE and/or T cell reactivity to the organism, demonstrating that Malassezia can act as an exacerbating factor [14].…”

A systematic literature review of the human skin microbiome as biomarker for dermatological drug development

“…The skin microbiome in patients with AD was assessed in 11 studies, Table 1 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66. A greater proportion of longitudinal studies and 2 completed randomized controlled trials were performed in AD patients.…”

The Malassezia Genus in Skin and Systemic Diseases

“…More than 20 studies (Tables 3 to 6) have been carried out worldwide on the epidemiology of Malassezia species in cases of pityriasis versicolor, seborrheic dermatitis, atopic eczema, and psoriasis and on healthy control skin of the same individuals or skin from healthy volunteers (53,63,89,112,122,146,171,173,180,185,228,237,255,259,275,286,344,353). Results are not directly comparable between studies, as different methodologies, isolation media, and identification procedures have been employed.…”