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Molecular analysis of Malassezia microflora on the skin of atopic dermatitis patients and healthy subjects.

ABSTRACT: Members of the genus Malassezia, lipophilic yeasts, are considered to be one of the exacerbating factors in atopic dermatitis (AD). We examined variation in cutaneous colonization by Malassezia species in AD patients and compared it with variation in healthy subjects. Samples were collected by applying transparent dressings to the skin lesions of AD patients. DNA was extracted directly from the dressings and amplified in a specific nested PCR assay. Malassezia-specific DNA was detected in all samples obtained from 32 AD patients. In particular, Malassezia globosa and M. restricta were detected in approximately 90% of the AD patients and M. furfur and M. sympodialis were detected in approximately 40% of the cases. The detection rate was not dependent on the type of skin lesion. In healthy subjects, Malassezia DNA was detected in 78% of the samples, among which M. globosa, M. restricta, and M. sympodialis were detected at frequencies ranging from 44 to 61%, with M. furfur at 11%. The diversity of Malassezia species found in AD patients was greater (2.7 species detected in each individual) than that found in healthy subjects (1.8 species per individual). Our results suggest that M. furfur, M. globosa, M. restricta, and M. sympodialis are common inhabitants of the skin of both AD patients and healthy subjects, while the skin microflora of AD patients shows more diversity than that of healthy subjects. To our knowledge, this is the first report of the use of a nested PCR as an alternative to fungal culture for analysis of the distribution of cutaneous Malassezia spp.

SUBMITTER: Sugita T

PROVIDER: S-EPMC88376 | biostudies-literature | 2001 Oct

REPOSITORIES: biostudies-literature

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Molecular analysis of Malassezia microflora on the skin of atopic dermatitis patients and healthy subjects.

Sugita T T Suto H H Unno T T Tsuboi R R Ogawa H H Shinoda T T Nishikawa A A

Journal of clinical microbiology 20011001 10

Members of the genus Malassezia, lipophilic yeasts, are considered to be one of the exacerbating factors in atopic dermatitis (AD). We examined variation in cutaneous colonization by Malassezia species in AD patients and compared it with variation in healthy subjects. Samples were collected by applying transparent dressings to the skin lesions of AD patients. DNA was extracted directly from the dressings and amplified in a specific nested PCR assay. Malassezia-specific DNA was detected in all sa ...[more]

PMID: 11574560

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Project description:BackgroundThe Malassezia yeasts which belong to the physiological microflora of human skin have also been implicated in several dermatological disorders, including pityriasis versicolor (PV), atopic dermatitis (AD), and psoriasis (PS). The Malassezia genus has repeatedly been revised and it now accommodates 14 species, all but one being lipid-dependent species. The traditional, phenotype-based identification schemes of Malassezia species are fraught with interpretative ambiguities and inconsistencies, and are thus increasingly being supplemented or replaced by DNA typing methods. The aim of this study was to explore the species composition of Malassezia microflora on the skin of healthy volunteers and patients with AD and PS.MethodsSpecies characterization was performed by conventional, culture-based methods and subsequently molecular techniques: PCR-RFLP and sequencing of the internal transcribed spacer (ITS) 1/2 regions and the D1/D2 domains of the 26S rRNA gene. The Chi-square test and Fisher's exact test were used for statistical analysis.ResultsMalassezia sympodialis was the predominant species, having been cultured from 29 (82.9%) skin samples collected from 17 out of 18 subjects under the study. Whereas AD patients yielded exclusively M. sympodialis isolates, M. furfur isolates were observed only in PS patients. The isolation of M. sympodialis was statistically more frequent among AD patients and healthy volunteers than among PS patients (P < 0.03). Whether this mirrors any predilection of particular Malassezia species for certain clinical conditions needs to be further evaluated. The overall concordance between phenotypic and molecular methods was quite high (65%), with the discordant results being rather due to the presence of multiple species in a single culture (co-colonization) than true misidentification. All Malassezia isolates were susceptible to cyclopiroxolamine and azole drugs, with M. furfur isolates being somewhat more drug tolerant than other Malassezia species.ConclusionsThis study provides an important insight into the species composition of Malassezia microbiota in human skin. The predominance of M. sympodialis in both normal and pathologic skin, contrasts with other European countries, reporting M. globosa and M. restricta as the most frequently isolated Malassezia species.

Project description:BackgroundEczema vaccinatum (EV), a disseminated viral skin infection, is a life-threatening complication of vaccinia virus (VV) inoculation in patients with atopic dermatitis (AD) and is thought to be associated with a defective innate immune response. However, the precise mechanism or mechanisms and key factor or factors of EV are unknown.ObjectiveGiven that patients with psoriasis, another inflammatory skin disorder, are not susceptible to EV, we compared the global transcriptional response of skin to VV in healthy subjects, patients with psoriasis, and patients with AD, focusing on AD-specific genes. We hypothesized that differences in the transcriptional response to VV between patients with AD and patients with psoriasis or healthy subjects would identify a defective pathway or pathways that might be associated with the development of EV.MethodsGene expression profiling of sham-treated and VV-treated unaffected skin explants from patients with AD (n = 12), patients with psoriasis (n = 12), or healthy subjects (n = 13) were generated with U133_Plus2 (54,613 probe sets) GeneChips and analyzed with the GCOS_1.4/SAM_2.1/MAPPFinder_2.0 pipeline.ResultsSixty-seven genes were significantly affected by VV in AD skin but not in psoriatic and healthy skin. Genes associated with defense response, response to wounding, and immune response were the most affected by VV in AD skin. All genes in these ontologies were downregulated, including the innate immunity genes leukotriene B(4) receptor (LTB4R), orosomucoid 1 (ORM1), coagulation factor II (thrombin) receptor (F2R), complement component 9 (C9), and LPS-binding protein (LBP). These findings were confirmed by means of real-time PCR and validated by means of PubMatrix analysis. ORM1, Toll-like receptor 4 (TLR4), and NLR family pyrin domain containing 1 (NLRP1) genes were also linked to AD severity.ConclusionThis study identified groups of innate immunity genes that are associated with the aberrant response of AD skin to VV and represent potential targets for EV pathogenesis.

Dataset Information

Molecular analysis of Malassezia microflora on the skin of atopic dermatitis patients and healthy subjects.

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Molecular analysis of Malassezia microflora on the skin of atopic dermatitis patients and healthy subjects.

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