The role of Malassezia furfur in dermatology

Microbiome: Role in Inflammatory Skin Diseases

As the body's largest organ, the skin harbors a highly diverse microbiota, playing a crucial role in resisting foreign pathogens, nurturing the immune system, and metabolizing natural products. The dysregulation of human skin microbiota is implicated in immune dysregulation and inflammatory responses. This review delineates the microbial alterations and immune dysregulation features in common Inflammatory Skin Diseases (ISDs) such as psoriasis, rosacea, atopic dermatitis(AD), seborrheic dermatitis(SD), diaper dermatitis(DD), and Malassezia folliculitis(MF).The skin microbiota, a complex and evolving community, undergoes changes in composition and function that can compromise the skin microbial barrier. These alterations induce water loss and abnormal lipid metabolism, contributing to the onset of ISDs. Additionally, microorganisms release toxins, like Staphylococcus aureus secreted α toxins and proteases, which may dissolve the stratum corneum, impairing skin barrier function and allowing entry into the bloodstream. Microbes entering the bloodstream activate molecular signals, leading to immune disorders and subsequent skin inflammatory responses. For instance, Malassezia stimulates dendritic cells(DCs) to release IL-12 and IL-23, differentiating into a Th17 cell population and producing proinflammatory mediators such as IL-17, IL-22, TNF-α, and IFN-α.This review offers new insights into the role of the human skin microbiota in ISDs, paving the way for future skin microbiome-specific targeted therapies.

The Prevalence, Associated Factors, and Clinical Characterization of Malassezia folliculitis in Patients Clinically Diagnosed with Acne Vulgaris

BACKGROUND

The clinical presentation of Malassezia folliculitis (MF) can imitate acne vulgaris (AV), making it difficult to distinguish between the two conditions. Moreover, MF can coexist with AV in the same patient. The incidence of MF in patients clinically diagnosed with AV may be underestimated. This study aimed to determine the prevalence, associated factors, and clinical characterization of MF patients diagnosed with AV.

MATERIALS AND METHODS

Three hundred twenty new acne patients were questioned regarding general information, including age, sex, itchy symptoms, and past treatment history with antibiotics and steroids within four weeks. Clinical presentations of AV (location and severity), dandruff, and seborrheic dermatitis were examined by a dermatologist. Cytologic studies to determine the abnormal proliferation of Malassezia yeasts were performed from pustules or, in the absence of pustules, comedo-like papules, and comedones. The smears were stained with methylene blue and evaluated under a light microscope by the researcher.

RESULTS

The prevalence of MF in patients clinically diagnosed with AV was 28.8% (95% Confidence interval: CI = 23.8% - 33.7%), which can be classified as 24.7% were AV with MF and the remaining 4.1% were MF only. This study revealed that patients diagnosed with MF were 7.38 times more likely to have itchy symptoms than patients diagnosed with AV. MF patients had 8.89 times and 9.17 times higher risk of acneiform lesions on the scalp/ hairline and upper back than those who did not have MF, respectively.

CONCLUSION

This present study revealed a high prevalence of MF in patients clinically diagnosed with AV. Dermatologists should be aware of MF when encountering AV patients with acneiform lesions on the scalp/ hairline and upper back with pruritus. Diagnosis based on clinical presentations alone may lead to misdiagnosis. Methylene blue staining is easy to perform and beneficial to diagnose MF.

The effect of tinea versicolor on thiol/disulphide homeostasis

Introduction

Tinea versicolor is a superficial fungal infection caused by Malassezia spp. Malassezia spp. is a member of the normal human skin flora. It becomes a pathogen by transforming from the yeast form to the mycelium form. The oxidant/antioxidant homeostasis may be responsible for this. Thiol/disulphide homeostasis is a new marker indicating oxidative stress. This homeostasis is affected in many illnesses.

Aim

To investigate the thiol/disulphide homeostasis in patients with tinea versicolor.

Material and methods

Forty-two patients with tinea versicolor (median age: 36 years, min.–max.: 19–58) and 36 healthy controls (median age: 32 years, min.–max.: 18–60) were included in the trial. The levels of native thiol, disulphide, and total thiol were measured by an automated method in the patient and control groups. Disulphide/total thiol, disulphide/native thiol and native thiol/total thiol rates were calculated as percentage.

Results

For the patient group and the control group, the native thiol levels were found to be 464.32 ±51.48 mmol/l and 465.18 ±51.32 mmol/l, disulphide levels – 19.80 ±7.08 mmol/l and 21.27 ±8.90 mmol/l, total thiol levels – 503.92 ±53.65 mmol/l and 508.07 ±56.59 mmol/l, respectively. No statistical difference was detected between the two groups.

Conclusions

Thiol/disulphide homeostasis was not affected in tinea versicolor. According to our findings, oxidative stress seems to have no role in the pathogenesis of tinea versicolor.

Molecular biological identification of malassezia yeasts using pyrosequencing

Background

A Pyrosequencing assay has been used in identification of fungal species such as Candida or Aspergillus and diagnosis of pathogenic bacteria such as Helicobacter pylori but there has been no report on successful isolation and identification of Malassezia yeasts using the pyrosequencing method.

Objective

Examine the applicability and plausibility of the pyrosequencing method in identification of the Malassezia species.

Methods

At internal transcribed spacer (ITS) sites 1 and 2, three primers were developed using Pyrosequencing Assay Design Software (Biotage AB). Pyrosequencing was performed on 11 standard strains and 83 genomic DNA samples obtained from 66 healthy controls aged from 1 to 80.

Results

The eleven Malassezia standard species and 83 genomic DNA samples were successfully identified using the pyrosequencing assay.

Conclusion

The pyrosequencing method is a new tool for analysis of Malassezia yeasts, and its precision and rapidity suggests its clinical applicability.

Epidemiologic Study of Malassezia Yeasts in Acne Patients by Analysis of 26S rDNA PCR-RFLP

Background

Although acne is a common follicular inflammatory dermatosis, studies of the relationship between Malassezia yeasts and acne have rarely been conducted.

Objective

We sought to identify Malassezia yeasts from acne patients and establish a relationship between specific types of species of Malassezia and acne.

Methods

Sixty acne patients were enrolled. Each strain obtained was identified as one of eleven species by 26S rDNA PCR-RFLP. We then compared these data with those of age- and sex-matched healthy subjects.

Results

Growth of Malassezia was evident in fewer patients with acne (50%) in comparison to controls (70.6%). M. restricta was dominant in patients with acne (23.9%), whereas M. globosa was most common (26.7%) in healthy controls. In the patients group, the rate was the highest (71.7%) in the twenties and, in terms of body site, the rate was the highest (60%) in the chest. In the control group, the rate was the highest (75.0%) in the thirties and in the forehead (85.0%).

Conclusion

The detection rate of Malassezia yeasts was conspicuously low in the acne patients group. Statistically significant differences were observed between the patient and the control groups in the twenties and thirties, and in terms of body site, in the forehead and chest.

Epidemiologic Study of Malassezia Yeasts in Patients with Malassezia Folliculitis by 26S rDNA PCR-RFLP Analysis

BACKGROUND

So far, studies on the inter-relationship between Malassezia and Malassezia folliculitis have been rather scarce.

OBJECTIVE

We sought to analyze the differences in body sites, gender and age groups, and to determine whether there is a relationship between certain types of Malassezia species and Malassezia folliculitis.

METHODS

Specimens were taken from the forehead, cheek and chest of 60 patients with Malassezia folliculitis and from the normal skin of 60 age- and gender-matched healthy controls by 26S rDNA PCR-RFLP.

RESULTS

M. restricta was dominant in the patients with Malassezia folliculitis (20.6%), while M. globosa was the most common species (26.7%) in the controls. The rate of identification was the highest in the teens for the patient group, whereas it was the highest in the thirties for the control group. M. globosa was the most predominant species on the chest with 13 cases (21.7%), and M. restricta was the most commonly identified species, with 17 (28.3%) and 12 (20%) cases on the forehead and cheek, respectively, for the patient group.

CONCLUSION

Statistically significant differences were observed between the patient and control groups for the people in their teens and twenties, and in terms of the body site, on the forehead only.

Molecular analysis of malassezia microflora on the skin of the patients with atopic dermatitis

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.

Isolation of 19 strains of Malassezia dermatis from healthy human skin in Korea

This research was conducted on the cultured samples of 160 healthy men and women aged 0-80 years without any skin disease. Nineteen clinical isolates of Malassezia dermatis showed positive in a catalase test and all grew in 0.5% Tween-60 and 0.1% Tween-80 added to 2% glucose/1% peptone culture medium. Round and ellipsoidal yeast cells and budding of the yeast cells were observed by microscopy, resembling Malassezia sympodialis, Malassezia furfur and Malassezia nana. The 26S rDNA polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) pattern was the same as for M. dermatis (JCM 11348), the standard strain. 26S rDNA and ITS1 sequencing were performed for exact identification, showing 99% accordance with M. dermatis (AB070361), M. dermatis (AB070356), confirming the species to be new and first to be reported in Korea. Taking a molecular biological classification approach by analyzing the 26S rDNA PCR-RFLP patterns, we have successfully isolated 19 cases of M. dermatis- the first in Korea.

The Investigation on the Distribution of Malassezia Yeasts on the Normal Korean Skin by 26S rDNA PCR-RFLP

BACKGROUND

Malassezia yeasts are normal flora of the skin that are discovered in 75~98% of health subjects, but since its association with various skin disorders have been known, many studies have been conducted in the distribution of the yeasts.

OBJECTIVE

To isolate, identify, and classify Malassezia yeasts from the normal human skin of Koreans by using the rapid and accurate molecular biology method (26S rDNA PCR-RFLP) which overcome the limits of morphological and biochemical methods, and to gather a basic database that will show its relation to various skin diseases.

METHODS

Malassezia yeasts were cultured from clinically healthy human skin using scrub-wash technique at five sites (forehead, cheek, chest, upper arm, and thigh) and swabbing technique at scalp in 160 participants comprised of 80 males and 80 females aged from 0 to 80. Identification of obtained strains were placed into the one of the 11 species by 26S rDNA PCR-RFLP.

RESULTS

An overall positive culture rate was 62.4% (599/960). As shown in the experiment groups by their age, the positive culture rate was the highest (74.2%) in the age 21~30 and 31~40 (89/120). In the experiment groups by different body areas, the scalp showed the highest positive culture rate of 90% (144/160). On analysis of 26S rDNA PCR-RFLP, M. globosa was the most predominant species in the age 0~10 (32.8%), 11~20 (28.9%), 21~30 (32.3%). M. restricta was identified as predominant species in the age 41~50 (27.9%), 61~70 (31.5%) and 71~80 (24.0%). In the age 31~40 years, M. sympodialis was found to be the most common species (24.6%). According to body site, M. restricta was more frequently recovered in the scalp (56.8%), forehead (39.8%) and cheek (24.0%) and while M. globosa was more frequently recovered in the chest (36.8%). Higher positive culture rates of Malassezia yeasts were shown in male subjects than female counterparts in all body areas except scalp (p<0.05). Especially in this study, M. dermatis, newly isolated Malassezia species from atopic dermatitis patient in Japan, was isolated and identified in 19 cases (1.9%) in healthy subjects.

CONCLUSION

The key is to recognize the existence of a difference in the type of Malassezia species in different ages as well as body areas, which reflects differing skin lipid levels in various ages and different body areas. Moreover, 26S rDNA PCR-RFLP analysis which was opted in this study could provide a sensitive and rapid identification system for Malassezia species, which may be applied to epidemiological surveys and clinical practice.

Identificação de espécies de Malassezia em pacientes com pitiríase versicolor em Goiânia-GO

O objetivo deste estudo foi verificar a freqüência de pitiríase versicolor e identificar leveduras do gênero Malassezia, de pacientes encaminhados ao laboratório de Micologia da Universidade Federal de Goiás em Goiânia. Foram diagnosticados 95 casos de pitíriase versicolor e identificados quatro espécies de Malassezia: Malassezia furfur, Malassezia sympodialis, Malassezia globosa e Malassezia obtusa.

Quantitative investigation on the distribution of Malassezia species on healthy human skin in Korea

This study concerns a culture research based on the data gathered from Korean subjects to examine distribution of Malassezia yeast. Malassezia yeast were cultivated out of samples from scalp, forehead, chest, arm and thigh. Malassezia restricta was recovered more frequently in the teens and young adults, while M. globosa was the predominant species in subjects older than 50 years of age. The population density of Malassezia yeast was significantly higher in the age group (AG) of 21-30 years compared with other AGs (P < 0.05). It was also significantly higher in the chest compared with the forehead, arm and thigh (P < 0.05). The key is to recognise the existence of a difference in the amount and type of Malassezia species in different AGs as well as body areas, which reflects differing skin lipid levels in various AGs and different body areas.

Molecular analysis of fungal microbiota in samples from healthy human skin and psoriatic lesions

Psoriasis, a common cutaneous disease of unknown etiology, may be triggered by infections, including those due to fungi. Since the fungal community of human skin is poorly characterized, we aimed to analyze the mycological microbiota in healthy skin and psoriatic lesions. Twenty-five skin samples from five healthy subjects (flexor forearm) and three patients with psoriasis were analyzed using broad-range 18S ribosomal DNA (rDNA) and 5.8S rDNA/internal transcribed spacer 2 (ITS2) Malassezia-specific PCR primers. Broad-range PCR analysis indicated that most organisms resembled Malassezia. Malassezia-specific 5.8S/ITS2 analysis of 1,374 clones identified five species and four unknown phylotypes, potentially representing new species. The species distribution appears largely host specific and conserved in different sites of healthy skin. In three subjects, the Malassezia microbiota composition appeared relatively stable over time. Samples of Malassezia microbiota from healthy skin and psoriatic lesions were similar in one patient but substantially different in two others. These data indicate the predominance of Malassezia organisms in healthy human skin, host-specific variation, stability over time, and as yet, no consistent patterns differentiating psoriatic skin from healthy skin.

Expression and potential function of cathelicidin antimicrobial peptides in dermatophytosis and tinea versicolor

OBJECTIVES

This study was designed to characterize the role of the human cathelicidin LL-37 in fungal skin infections such as dermatophytosis and tinea versicolor.

METHODS

The in vitro antimicrobial activity of synthetic antimicrobial peptides including the human cathelicidin LL-37 against Malassezia furfur and several dermatophytes was determined. Immunostaining was performed to determine expression of cathelicidin in skin biopsies from patients with tinea pedis, tinea corporis and tinea versicolor. Cathelicidin peptide expression was evaluated by western blotting and mRNA expression was studied in keratinocytes exposed to M. furfur or Trichophyton rubrum.

RESULTS

LL-37 inhibits the growth of fungi with an MIC of 20-30 microM for M. furfur and 12.5 microM for Trichophyton mentagrophytes and T. rubrum. LL-37 also shows fungicidal activity with a minimum fungicidal concentration (MFC) of 12.5 and 25 microM for T. mentagrophytes and T. rubrum, respectively. An increase in cathelicidin expression was observed in human skin tissue infected with fungi compared with healthy skin. Western blotting of skin scrapings demonstrated that human cathelicidin is processed from its precursor into an active peptide in both healthy and infected plantar skin.

CONCLUSIONS

These findings support a hypothesis that antimicrobial peptides such as cathelicidins can play a role in skin defence against dermatophytes and M. furfur.

Prevalence of male and female pattern hair loss in Maryborough

Maryborough, in central Victoria has an approximate population of 8000 and census data is well matched for Australia overall. Australia has compulsory voting and registration on the electoral roll. To determine the age-related prevalence of balding among men and women in Maryborough we conducted a postal survey of 5000 men and women aged 20 or older, and 427 were invited to attend for examination. Additional data was collected on dandruff, presence of gray hair. Supplementary questionnaires were sent to 340 children aged 5-9, attending a coeducational primary school. 1456 adults (34.1%) responded to the questionnaire. 396 attended for examination. The prevalence of androgenetic alopecia (AGA) increased with advancing age. 98.6% of men had bitemporal recession and severity was significantly associated with vertex and mid-frontal hair loss (p <0.01) but not age (p = 0.06). In all, 64.4% of women had bitemporal hair loss, and similar to men there was a significant association with mid-frontal hair loss (p =0.042) but not age (p =0.467). One hundred and forty children with completed questionnaires were examined. All 72 females and 68 males were assessed as stage 1 on the mid-line part and with no bitemporal recession (frequency stage 1 = 100%, 95% CI (confidence interval) 97.4%-100%). A significant but weak positive association existed between presence of gray hair and history of dandruff (p<0.01). The prevalence of mid-frontal hair loss increases with age and affects 57% of women and 73.5% of men aged 80 and over.

Itraconazole in the treatment of seborrheic dermatitis: a new treatment modality

BACKGROUND

Due to the high rate of recurrence, seborrheic dermatitis (SD) represents a therapeutic problem.

AIM

To evaluate the role of oral itraconazole in the treatment of SD.

PATIENTS AND METHODS

Thirty-two patients with SD were enrolled in the study. All topical and oral treatments were stopped. The patients applied 1% hydrocortisone cream twice daily for 1 month. In addition, they took itraconazole, 200 mg/day, during the first week of the first month and then hydrocortisone cream was stopped and itraconazole (200 mg/day) was given on the first 2 days of the following 11 months. The patients were followed for 2 months without medicine. The severity score was measured at the initial evaluation, and at the first, 12th, and 14th months.

RESULTS

Twenty-eight patients completed the study. There was a statistically significant decrease in the mean severity score at the first, 12th, and 14th months. On the final evaluation at the 12th month, 19 of the 28 patients showed a complete improvement, and three patients showed a slight improvement.

CONCLUSIONS

This study indicates that itraconazole plays an important role in the treatment of SD.

Adenovirus-mediated gene transfer to keratinocytes--a review

The introduction and expression of a foreign gene provide a powerful tool for investigating functions and regulation of a gene of interest; however, keratinocytes have a major drawback in that foreign genes are hardly transfected by conventional methods and stable transformants are most difficult to establish in normal keratinocytes with a limited short life span. To overcome these problems, we used an adenovirus vector, Ax, developed by Saito et al, which yields desired recombinant viruses at an efficiency about 100-fold that of conventional methods, and by which genes are expressed at a high level under the control of a composite CAG promoter. We established Ax vectors carrying various isoforms of protein kinase C (PKC). Using these vectors, we found that the eta and delta isoforms of PKC, but not the alpha and zeta isoforms, mediate terminal differentiation in normal human keratinocytes. These Ax-vectors are also applicable to organ culture of mouse embryos. Advantages and disadvantages of adenovirus vectors and their use for keratinocyte biology are reviewed.