Skin diseases associated with Malassezia yeasts: facts and controversies

Advances in the diagnosis and therapeutic management of atopic dermatitis

Atopic dermatitis is a very prevalent disease that affects children as well as adults. The disease has a severe impact on quality of life for the patients and their families. The skin in atopic dermatitis patients is a site of both a severe inflammatory reaction dominated by lymphocytes and decreased skin barrier function. The treatment of the disease is mainly aimed at reducing the inflammation in the skin and/or restoring the skin barrier function. However, most of the treatments used today singularly aim at reducing the inflammation in the skin. Depending on the severity of the disease, the anti-inflammatory treatment may be topical or systemic, but basic treatment, no matter the severity, should always be emollients. In addition, new studies have shown good effects of psychosocial interventions, such as eczema schools, for patients and their families. This review covers the latest trends in the treatment of atopic dermatitis.

Topical antifungals for seborrhoeic dermatitis

BACKGROUND

Seborrhoeic dermatitis is a chronic inflammatory skin condition that is distributed worldwide. It commonly affects the scalp, face and flexures of the body. Treatment options include antifungal drugs, steroids, calcineurin inhibitors, keratolytic agents and phototherapy.

OBJECTIVES

To assess the effects of antifungal agents for seborrhoeic dermatitis of the face and scalp in adolescents and adults.A secondary objective is to assess whether the same interventions are effective in the management of seborrhoeic dermatitis in patients with HIV/AIDS.

SEARCH METHODS

We searched the following databases up to December 2014: the Cochrane Skin Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 11), MEDLINE (from 1946), EMBASE (from 1974) and Latin American Caribbean Health Sciences Literature (LILACS) (from 1982). We also searched trials registries and checked the bibliographies of published studies for further trials.

SELECTION CRITERIA

Randomised controlled trials of topical antifungals used for treatment of seborrhoeic dermatitis in adolescents and adults, with primary outcome measures of complete clearance of symptoms and improved quality of life.

DATA COLLECTION AND ANALYSIS

Review author pairs independently assessed eligibility for inclusion, extracted study data and assessed risk of bias of included studies. We performed fixed-effect meta-analysis for studies with low statistical heterogeneity and used a random-effects model when heterogeneity was high.

MAIN RESULTS

We included 51 studies with 9052 participants. Of these, 45 trials assessed treatment outcomes at five weeks or less after commencement of treatment, and six trials assessed outcomes over a longer time frame. We believe that 24 trials had some form of conflict of interest, such as funding by pharmaceutical companies.Among the included studies were 12 ketoconazole trials (N = 3253), 11 ciclopirox trials (N = 3029), two lithium trials (N = 141), two bifonazole trials (N = 136) and one clotrimazole trial (N = 126) that compared the effectiveness of these treatments versus placebo or vehicle. Nine ketoconazole trials (N = 632) and one miconazole trial (N = 47) compared these treatments versus steroids. Fourteen studies (N = 1541) compared one antifungal versus another or compared different doses or schedules of administration of the same agent versus one another. KetoconazoleTopical ketoconazole 2% treatment showed a 31% lower risk of failed clearance of rashes compared with placebo (risk ratio (RR) 0.69, 95% confidence interval (CI) 0.59 to 0.81, eight studies, low-quality evidence) at four weeks of follow-up, but the effect on side effects was uncertain because evidence was of very low quality (RR 0.97, 95% CI 0.58 to 1.64, six studies); heterogeneity between studies was substantial (I² = 74%). The median proportion of those who did not have clearance in the placebo groups was 69%.Ketoconazole treatment resulted in a remission rate similar to that of steroids (RR 1.17, 95% CI 0.95 to 1.44, six studies, low-quality evidence), but occurrence of side effects was 44% lower in the ketoconazole group than in the steroid group (RR 0.56, 95% CI 0.32 to 0.96, eight studies, moderate-quality evidence).Ketoconozale yielded a similar remission failure rate as ciclopirox (RR 1.09, 95% CI 0.95 to 1.26, three studies, low-quality evidence). Most comparisons between ketoconazole and other antifungals were based on single studies that showed comparability of treatment effects. CiclopiroxCiclopirox 1% led to a lower failed remission rate than placebo at four weeks of follow-up (RR 0.79, 95% CI 0.67 to 0.94, eight studies, moderate-quality evidence) with similar rates of side effects (RR 0.9, 95% CI 0.72 to 1.11, four studies, moderate-quality evidence). Other antifungalsClotrimazole and miconazole efficacies were comparable with those of steroids on short-term assessment in single studies.Treatment effects on individual symptoms were less clear and were inconsistent, possibly because of difficulties encountered in measuring these symptoms.Evidence was insufficient to conclude that dose or mode of delivery influenced treatment outcome. Only one study reported on treatment compliance. No study assessed quality of life. One study assessed the maximum rash-free period but provided insufficient data for analysis. One small study in patients with HIV compared the effect of lithium versus placebo on seborrhoeic dermatitis of the face, but treatment outcomes were similar.

AUTHORS' CONCLUSIONS

Ketoconazole and ciclopirox are more effective than placebo, but limited evidence suggests that either of these agents is more effective than any other agent within the same class. Very few studies have assessed symptom clearance for longer periods than four weeks. Ketoconazole produced findings similar to those of steroids, but side effects were fewer. Treatment effect on overall quality of life remains unknown. Better outcome measures, studies of better quality and better reporting are all needed to improve the evidence base for antifungals for seborrhoeic dermatitis.

The Prevalence and Species Composition of Malassezia yeasts in Patients with Clinically Suspected Onychomycosis

Introduction:

There are limited numbers of studies which focused on the identification of Malassezia yeasts to a species level in onychomycosis. Therefore, the aim of our study was to determine the prevalence and species composition of Malassezia yeasts in patients with clinically suspected onychomycosis and to examine if the range of species varies with patient gender, age, site of involvement and clinical pattern of onychomycosis.

Methods:

Specimens were taken from 785 patients presenting signs of onychomycosis and then incubated on Sabouraud dextrose agar and modified Dixon agar. The yeasts isolated were identified according to their macroscopic and microscopic features and physiological characteristics.

Results:

Malassezia species were diagnosed both by microscopy and culture in fourteen (1.8%) patients. M. globosa was the predominant, if not only, species identified from nail samples. Mixed cultures were observed in five cases: in 4 cases Malassezia was co-isolated with Candida albicans and in one case with dermatophyte. Fingernails were affected more frequently than toenails (85.7%) and distolateral subungual onychomycosis was the most common clinical type (78.6%).

Conclusion:

No significant differences were found in the distribution of Malassezia species isolated according to demographic parameters.

Are Demodex mites principal, conspirator, accomplice, witness or bystander in the cause of rosacea?

As the only permanent human ectoparasite, the role of human Demodex mites in health and diseases remains largely unclarified. In view of the ecological interaction between organisms of two different species, a type of commensalism between Demodex mites and humans (the former benefit, the latter unaffected) is most likely, while parasitism occurs temporarily and spatially in the diseased state (the former benefit, the latter harmed). As part of normal skin microbiota, the causal role of Demodex mites in the initiation of rosacea can neither fulfill the classical Henle-Koch's principal nor the advanced criteria proposed by Fredericks and Relman for molecular detection of non-cultivatable microorganisms. Epidemiological analysis using Hill's criteria fails to support the causative role of Demodex mites in rosacea regarding the strength of association, specificity and temporality of association, biological gradient and plausibility as well as clinical coherence, therapeutic experimentation and medical analogy. In application of Rothman's sufficient cause model to evaluate the contribution of Demodex mites to rosacea on a population basis, Demodex mites can be regarded as a non-necessary, non-sufficient causal factor for certain forms of rosacea. Further strategies to dissect the association between Demodex mites and rosacea may include studying the possible existence of more virulent forms of mites with a higher pathogenicity, the endosymbiotic bacteria in certain life periods of mites, the interactions between mites and human hosts or between mites and environment, and to set up ex vivo culture models for Demodex mites.

Antimicrobial photodynamic therapy: an effective alternative approach to control fungal infections

Skin mycoses are caused mainly by dermatophytes, which are fungal species that primarily infect areas rich in keratin such as hair, nails, and skin. Significantly, there are increasing rates of antimicrobial resistance among dermatophytes, especially for Trichophyton rubrum, the most frequent etiologic agent worldwide. Hence, investigators have been developing new therapeutic approaches, including photodynamic treatment. Photodynamic therapy (PDT) utilizes a photosensitive substance activated by a light source of a specific wavelength. The photoactivation induces cascades of photochemicals and photobiological events that cause irreversible changes in the exposed cells. Although photodynamic approaches are well established experimentally for the treatment of certain cutaneous infections, there is limited information about its mechanism of action for specific pathogens as well as the risks to healthy tissues. In this work, we have conducted a comprehensive review of the current knowledge of PDT as it specifically applies to fungal diseases. The data to date suggests that photodynamic treatment approaches hold great promise for combating certain fungal pathogens, particularly dermatophytes.

Gut fungal microbiota: the Yin and Yang of inflammatory bowel disease

The prevalence of inflammatory bowel diseases (IBD) has been steadily increasing since 1960. They are widespread throughout Europe, North America, China, and Japan and are emerging as a global disease. The equilibrium among epithelial cells, the immune system, and the related microbiota seems to be paramount in ensuring the absence of these IBD. The role of bacteria in the setting of the gut microbiota has been thoroughly documented, but the role of fungi, which are less abundant, needs to be investigated. Our understanding of the fungal microbiota composition and its impact on IBD has greatly increased in the past 8 years. In this review, we compiled data obtained for the composition of fungal gut microbiota. Special attention was paid to the various effects of this microbial community on the IBD, i.e., the mechanisms and immune pathways involved in these interactions.

Malassezia intra-specific diversity and potentially new species in the skin microbiota from Brazilian healthy subjects and seborrheic dermatitis patients

Malassezia yeasts are part of the resident cutaneous microbiota, and are also associated with skin diseases such as seborrheic dermatitis (SD). The role these fungi play in skin diseases and why they are pathogenic for only some individuals remain unclear. This study aimed to characterize Malassezia microbiota from different body sites in healthy and SD subjects from Brazil. Scalp and forehead samples from healthy, mild SD and severe SD subjects were collected. Non-scalp lesions from severe SD patients were also sampled. 5.8S rDNA/ITS2 amplicons from Malassezia sp. were analyzed by RFLP and sequencing. Results indicate that Malassezia microbiota did not group according to health condition or body area. Phylogenetic analysis revealed that three groups of sequences did not cluster together with any formally described species, suggesting that they might belong to potential new species. One of them was found in high proportions in scalp samples. A large variety of Malassezia subtypes were detected, indicating intra-specific diversity. Higher M. globosa proportions were found in non-scalp lesions from severe SD subjects compared with other areas, suggesting closer association of this species with SD lesions from areas other than scalp. Our results show the first panorama of Malassezia microbiota in Brazilian subjects using molecular techniques and provide new perspectives for further studies to elucidate the association between Malassezia microbiota and skin diseases.

Autoallergy in atopic dermatitis

The term autoallergy denotes autoimmunity accompanying an atopic disease, with antigen-specific IgE as a hallmark. This phenomenon is discussed to contribute to a chronification of the disease and to shape the immune response in chronic atopic dermatitis (AD). In this review, we highlight recent insights into the autoallergic inflammation in AD. Different mechanisms underlying the allergenicity of autoallergens are discussed at the moment: intrinsic functions modulating the immune system as well as molecular mimicry may influence the allergenic potential of these proteins. Finally, the role of specific T cells is discussed.

Cite this as: Hradetzky S, Werfel T, Roesner LM. Autoallergy in atopic dermatitis. Allergo J Int 2015; 24:16–22 DOI: 10.1007/s40629-015-0037-5

Systemic treatment of seborrheic dermatitis with retinol palmitate

The goal of the study. Evaluating of the effectiveness of treatment of men with a diagnosis «Seborrheic dermatitis of the scalp» by the system using of retinol palmitate. Material and methods. 36 patients every day for 2 months received overnight per os 200000 ME of retinol palmitate, and in the comparison group (39 people) antiseborrheic shampoos have been used. The dynamics of severity of skin oiliness, pruritis, erythema, peeling, infiltration, excoriations has been evaluated in points. Before and after the treatment a histological and morphometric study of biopsy material from the affected areas has been carried.The terms of relapses have been set. Results. Retinol palmitate treatment efficiency - 91.7%, antiseborrheic shampoos - 84.6%. Along with the regression of symptoms of the disease in both groups after retinol palmitate treatment significantly declined oiliness of skin; the sizes of sebaceous glands acini and the presence of differentiated sebocytes, the squares of lymphocytic-macrophage clusters in the dermis, the number of keratinocytes with vacuolated cytoplasm have been reduced. Relapses of the disease during a year occured more rare - in 21 patients out of 32 (in the comparison group- in 25 out of 31) and at a later date (in the first 3 months in 2 patients out of 32, in comparison group in 10 out of 31). Identified effects were due to the action of retinol palmitate on the morphogenesis of the sebaceous glands.

The cross-talk between opportunistic fungi and the mammalian host via microbiota's metabolism

An increased understanding of the importance of microbiota in shaping the host's immune and metabolic activities has rendered fungal interactions with their hosts more complex than previously appreciated. It is now clear that a three-way interaction between host, fungi, and microbiota dictates the types of host-fungus relationship. Indeed, microbial dysbiosis predisposes to a variety of chronic fungal infections and diseases at local and distant sites. By correlating changes in metabolite profiles with microbiota metagenomic composition, we have defined a functional node whereby certain bacteria species contribute to host-fungal symbiosis and mucosal homeostasis. A tryptophan catabolic pathway is exploited by commensal lactobacilli and the mammalian host to increase fitness in response to Candida albicans by inducing resistance and tolerance mechanisms of antifungal immunity. Much like lactobacilli in the gut, Firmicutes change significantly in the airways during aspergillosis. The aryl hydrocarbon receptor has a pivotal role in connecting tryptophan catabolism by microbial communities and the host's own pathway of tryptophan degradation through the enzyme indoleamine 2,3-dioxygenase 1. These data suggest that the study of the human microbiota in the trans-omics era, with a focus on metagenomics and metabonomics, is providing novel insights into the regulation of host immune responsiveness to fungi.

The relationships between environmental bacterial exposure, airway bacterial colonization, and asthma

PURPOSE OF REVIEW

Recent application of advanced culture-independent molecular techniques for the identification of microorganisms has contributed to our knowledge on the role of early-life microbial exposure and colonization in health and disease. The purpose of this review is to present the current perspectives regarding the role of microbial exposure and airway bacterial colonization on the development and the activity of asthma.

RECENT FINDINGS

Recent findings continue to support the protective role of early-life diverse microbial exposure against the development of atopic diseases. However, airway bacterial colonization early in life serves as a risk factor for the development of asthma. Culture-independent molecular techniques for the identification of microorganisms have challenged the traditional paradigm that the lower airway is a sterile compartment. Asthmatics, compared with nonasthmatics, appear to have a different lung microbiome composition and some of these differences might contribute to asthma activity, severity, and corticosteroid response.

SUMMARY

Bacterial presence in the airway appears to influence the inception and may affect the activity of asthma. Complex interactions between different types and routes of bacterial exposures, the airway, and the immune system early in life may determine whether these exposures augment or reduce the risk of asthma development.

Association of Malassezia species with psoriatic lesions

The aetiology of psoriasis remains elusive. Among multiple factors hypothesised, association of Malassezia spp. is supported by response to topical antifungals. The objective of this study was to evaluate the association of Malassezia spp. with psoriatic lesion. The subjects included 50 consecutive patients with psoriasis, and 50 age- and sex-matched healthy controls. Samples were collected using scotch tape over one square inch area from the lesional and non-lesional sites. The isolated Malassezia spp. were identified by phenotypic methods and confirmed by ITS2 PCR-RFLP and sequencing of D1/D2 region of 26S rDNA. Psoriatic lesions were seen commonly on scalp (28%, 14), chest (22%, 11) and arms (16%, 8). Majority of cases presented with chronic plaque form (76%, 38; P < 0.05). From psoriatic lesions, most frequently isolated Malassezia species was M. furfur (70.6%, 24), followed by M. japonica (11.8%, 4) and M. globosa (8.8%, 3). From healthy individuals M. furfur, M. sympodialis, mixture of M. furfur and M. globosa was isolated in 73.3%, 10% and 16.7% (22, 3 and 5) of cases respectively. The average number of colonies isolated from scalp lesions of the patients was significantly higher (P = 0.03) than healthy areas. Although no strong association of Malassezia species was formed with psoriatic lesion in general, the fungi may play a role in exacerbation of scalp psoriasis.