Prevalence of sensitization to Malassezia spp. in adults with atopic dermatitis and psoriasis and its correlation with disease severity / Prevalência da sensibilização a Malassezia spp. em pacientes adultos portadores de dermatite atópica e psoríase e sua correlação com a gravidade das doenças

Fundamentals: Atopic Dermatitis (AD) and Psoriasis (PS) share clinical and physiopathological similarities. Objective: Determine the prevalence of sensitization to Malassezia spp. in adults with AD and PS and its correlation with disease severity. Methods: A cross-sectional study was carried out from January 2016 to August 2017 with adults. Malassezia spp.-specific IgE dosages were measured, and skin scrapings for fungal culture performed. Parametric or nonparametric tests were used for analysis. Results: Median age of the 20 participants with AD was 29 years old, and the mean SCO-RAD was 45.35 ± 18.32. Malassezia spp.- specific IgE median dosage was 0.63 kU/l. M. furfur and M. sympodialis were isolated. Spearman's nonparametric correlation analysis showed no correlation between sensitization to Malassezia spp. and disease severity. The median age of the 36 participants with PS was 61 years old, the median body surface area affected was 22%, and Malassezia spp.-specific IgE median dosage was 0.00 kU/l. M. furfur and Malassezia spp. were identified. Study limitations: Assessing the sensitization to Malasseziaspp. was difficult due to the reduced number of participants in the study. Furthermore, there was no uniformity in the location to collect skin scrapings. The use of topical medication was not suspended before collecting skin specimens for mycological examination, therefore interfer-ing with fungal isolation. Conclusion: Sensitization to Malassezia spp. was only detected in the AD sample. Malassezia spp.-specific IgE test did not prove to be a marker for disease severity in our AD sample (AU)

Fundamentos: Dermatite atópica (DA) e psoríase apresentam similaridades clínicas e fisiopatológicas. Objetivos: Avaliar a frequência da sensibilização a Malasseziaspp. em adultos portadores de DA e psoríase e correlacionar à gra-vidade dos quadros clínicos. Métodos: De janeiro de 2016 a agosto de 2017, conduziu-se um estudo observacional em indivíduos adultos onde foram realizadas dosagem de IgE específica anti-Malassezia spp. e raspados das lesões para cultura micológica. Testes paramétricos ou não paramétricos foram utilizados para análise. Resultados: Nos 20 portadores de DA, a mediana da idade foi 29 anos. O valor médio do Scoring Atopic Dermatitis foi 45,35 ± 18,32. A mediana de IgE específica anti-Malasseziaspp. foi 0,63 kU/l. M. furfur e M. sympodialis foram isolados. A análise de correlação não-paramétrica de Spearman não mostrou correlação entre a sensibilização à Malassezia spp. e a gra-vidade. Nos 36 pacientes com psoríase, foram obtidas as seguintes medianas: idade 61 anos, comprometimento de superfície corpórea 22% e IgE específica anti-Malassezia spp. 0,00 kU/l. Houve identificação de M. furfur e Malasse-zia spp. Limitações do estudo: O número reduzido de participantes dificultou a avaliação da sensibilização por IgE a Malasseziaspp. Não houve uniformidade nos locais de coleta dos raspados cutâneos. Medicamentos tópicos não foram suspensos anteriormente ao exame micológico, prejudicando o isolamento dos fungos. Conclusões: Sensibili-zação a Malassezia spp. apenas ocorreu nos portadores de DA. O teste de IgE específica anti-Malassezia spp. não se mostrou um marcador de gravidade para a DA neste grupo (AU)

Effect of chlorogenic and gallic acids combined with azoles on antifungal susceptibility and virulence of multidrug-resistant Candida spp. and Malassezia furfur isolates.

Chlorogenic acid (CHA) and gallic acid (GA) are safe natural phenolic compounds that are used as enhancers of some drugs in influencing antioxidant, anticancer, and antibacterial activities. Among fungi, Candida spp. and Malassezia spp. are characterized by an increasing prevalence of multidrug resistance phenomena and by a high morbidity and mortality of their infections. No data are available about the efficacy of CHA and GA combined with azoles on the antifungal susceptibility and on the virulence of both fungi. Therefore, their antifungal and antivirulence effects have been tested in combination with fluconazole (FLZ) or ketoconazole (KTZ) on 23 Candida spp. and 8 M. furfur isolates. Broth microdilution chequerboard, time-kill studies, and extracellular enzymes (phospholipase and hemolytic) activities were evaluated, displaying a synergistic antifungal action between CHA or GA and FLZ or KTZ on C. albicans, C. bovina, and C. parapsilosis, and antagonistic antifungal effects on M. furfur and Pichia kudriavzevii (Candida krusei) isolates. The time-kill studies confirmed the chequerboard findings, showing fungicidal inhibitory effect only when the GA was combined with azoles on Candida strains. However, the combination of phenolics with azoles had no effect on the virulence of the tested isolates. Our study indicates that the combination between natural products and conventional drugs could be an efficient strategy for combating azole resistance and for controlling fungistatic effects of azole drugs.

Malassezia Yeasts in Veterinary Dermatology: An Updated Overview.

Lipophilic yeasts of the genus Malassezia are important skin commensals and opportunistic skin pathogens in a variety of animals. The species M. pachydermatis was first isolated from the skin of a captive Indian rhinoceros with an exfoliative dermatitis in 1925, recognized as an important otic pathogen of dogs in the 1950's, and finally accepted, after several years of controversy, as a common cause of canine dermatitis in the 1990's. Since then, there has been considerable research into the biology of Malassezia yeasts and their interaction with their animal hosts. In dogs and cats, M. pachydermatis is associated with ceruminous otitis externa and a "seborrhoeic" dermatitis, wherein pruritic, erythematous skin lesions, often with brown/black greasy, malodourous material matting hairs, preferentially develop in intertriginous areas. Skin disease is favored by folds, underlying hypersensitivity disorders, endocrinopathies, defects of cornification, and in cats, various visceral paraneoplastic syndromes. Diagnosis is based on detecting the yeast in compatible skin lesions, usually by cytology, and observing a clinical and mycological response to therapy. Treatment normally comprises topical or systemic azole therapy, often with miconazole-chlorhexidine shampoos or oral itraconazole or ketoconazole. Management of concurrent diseases is important to minimize relapses. Historically, wild-type Malassezia isolates from dogs and cats were typically susceptible to azoles, with the exception of fluconazole, but emerging azole resistance in field strains has recently been associated with either mutations or quadruplication of the ERG11 gene. These observations have prompted increased interest in alternative topical antifungal drugs, such as chlorhexidine, and various essential oils. Further clinical trials are awaited with interest.

Seborrheic dermatitis-Looking beyond Malassezia.

Seborrhoeic Dermatitis (SD) is a very common chronic and/or relapsing inflammatory skin disorder whose pathophysiology remains poorly understood. Yeast of the genus Malassezia has long been regarded as a main predisposing factor, even though causal relationship has not been firmly established. Additional predisposing factors have been described, including sebaceous activity, host immunity (especially HIV infection), epidermal barrier integrity, skin microbiota, endocrine and neurologic factors, and environmental influences. Genetic studies in humans and mouse models-with particularly interesting insights from examining the Mpzl3 knockout mice and their SD-like skin phenotype, and patients carrying a ZNF750 mutation-highlight defects in host immunity, epidermal barrier and sebaceous activity. After synthesizing key evidence from the literature, we propose that intrinsic host factors, such as changes in the amount or composition of sebum and/or defective epidermal barrier, rather than Malassezia, may form the basis of SD pathobiology. We argue that these intrinsic changes provide favourable conditions for the commensal Malassezia to over-colonize and elicit host inflammatory response. Aberrant host immune activity or failure to clear skin microbes may bypass the initial epidermal or sebaceous abnormalities. We delineate specific future clinical investigations, complemented by studies in suitable SD animal models, that dissect the roles of different epidermal compartments and immune components as well as their crosstalk and interactions with the skin microbiota during the process of SD. This research perspective beyond the conventional Malassezia-centric view of SD pathogenesis is expected to enable the development of better therapeutic interventions for the management of recurrent SD.

Mechanisms of microbial pathogenesis and the role of the skin microbiome in psoriasis: A review.

The pathogenesis of psoriasis may involve a breakdown of immune tolerance to cutaneous microorganisms. Psoriasis is associated with a higher incidence of Crohn disease and periodontitis, two diseases involving impaired tolerance and abnormal immune activation in response to intestinal and oral microbiota, respectively. In addition, guttate and chronic plaque psoriasis are associated with Streptococcus pyogenes colonization. The aim of this review is to characterize the microorganisms implicated in psoriasis by examining results of major association studies and possible mechanisms of pathogenesis. Although studies show relative increases in Streptococcus and Staphylococcus and decreases in Malassezia and Cutibacterium, they differ in methods of sampling and methods of microbial analysis. As such, no definitive associations between microbes and psoriasis have been found to date. It also remains unclear if changes in the microbiomal composition have a causal association with psoriasis or are simply a consequence of the inflammatory microenvironment. Techniques enabling strain-level analysis rather than species-level analysis of the skin microbiome are likely necessary to determine microbiomal signatures of psoriasis. Future investigations may lead to new diagnostic tests and novel treatments, such as probiotics or bacterial transplantation.

Malassezia pachydermatis from animals: Planktonic and biofilm antifungal susceptibility and its virulence arsenal.

The yeast Malassezia pachydermatis is a component of the microbiota of dogs and cats, however it can cause otitis and seborrheic dermatitis in these animals. The objective of this study was to determine the antifungal susceptibility, and evaluate virulence and pathogenicity of 25 M. pachydermatis strains from animals. Susceptibility to ketoconazole, fluconazole, itraconazole, voriconazole, terbinafine, and amphotericin B was evaluated by broth microdilution assay. In addition, biofilm-forming ability, protease, phospholipase, hemolysin and melanin production and adhesion to epithelial cells by this yeast species were assessed. Finally, strain pathogenicity was investigated using the nematode Caenorhabditis elegans. Concerning the planktonic susceptibility, minimum inhibitory concentrations varied from <0.03 to>64 µg/mL for azole derivatives, 1 to >16 µg/mL for amphotericin B and 0.03 to 0.25 µg/mL for terbinafine. All strains were classified as strong biofilm producers, and ketoconazole, fluconazole and amphotericin B presented the best inhibitory effect against mature biofilms. All fungal isolates produced proteases, whereas 14/25 strains were positive for phospholipase production. Hemolytic activity was not observed and 18/25 strains showed dark pigmentation in the presence of L-DOPA. Regarding adhesion to epithelial cells, a low adhesion rate was observed in 10/12 evaluated strains. C. elegans mortality rate reached 95.9% after 96 h of exposure of the worms to M. pachydermatis. This yeast species produces important virulence factors and presents high pathogenicity, corroborating its clinical importance.

Dermatitis facial por Malassezia pachydermatis / Facial dermatitis caused by Malassezia pachydermatis

Se presenta un caso de dermatitis facial por Malassezia pachydermatis en un paciente de 34 años de edad, diagnosticado mediante clínica y estudio micológico. M. pachydermatis es una levadura que forma parte de la microbiota de mamíferos domésticos y animales salvajes, donde frecuentemente puede provocar dermatitis y otitis externa. En humanos, son escasas las infecciones por este agente, describiéndose desde infecciones superficiales hasta fungemias. En Chile se la ha encontrado como agente causal de pitiriasis versicolor y dermatitis seborreica principalmente en pacientes inmunocomprometidos.

We present a clinical case of facial dermatitis due to Malassezia pachydermatis in a patient of 34 years old, diagnosed by clinical and micology study. M. pachydermatis is a zoofilic yeast that is part of the microbiota of domestic mammals and wild animals, frequently causing dermatitis and external otitis. In humans, infections by this agent are very scarce, describing from superficial infections to fungemias. In Chile it has been found as causal agent of pitiriasis versicolor and seborrheic dermatitis mainly in inmunocompromised patients.

Especies del género Malassezia en piel sana de niños y adolecentes con VIH-SIDA / Malassezia species on healthy skin of children and teens with HIV / AIDS

Antecedentes: Las especies del género Malassezia forman parte de la biota cutánea normal humana y pueden ser aisladas en áreas ricas en glándulas sebáceas. Su colonización es alta durante edad prepuberal y puberal debido al aumento de actividad de dichas glándulas. Objetivo: Determinar la colonización por especies del género Malassezia en piel sana de niños y adolescentes con VIH/SIDA. Metodología: Las muestras fueron tomadas mediante el método de la impronta con cinta adhesiva transparente, en cuero cabelludo, pabellón auricular, pecho, espalda, muslo, antebrazo, palma de la mano e inoculadas en el medio con base de goma Spondia dulcis. La identificación de las especies se realizó siguiendo las claves descritas por Guého et al. Se realizó el test de difusión en tween propuesto por Guillot et al, la prueba de la catalasa, y la utilización de triptófano como fuente única de nitrógeno. Resultados: De un total de 80 niños y adolescentes, solo 23(28.75 por ciento) de ellos se les aisló Malassezia. 10 (43.48 por ciento) de sexo masculino y 13 (56.52 por ciento) de sexo femenino. Solo se encontró, Malassezia sympodialis con un predominio del 100 por ciento. Correspondiendo al mayor porcentaje de positividad al grupo etario de 4-7 años (56.52 por ciento). Las localizaciones anatómicas predominantes fueron: pabellón auricular (25.5 por ciento) seguida de pecho (21.3 por ciento) y espalda (19.1 por ciento). Conclusiones: En niños con HIV/SIDA se observa un patrón de colonización por M. sympodialis.

Background: Malassezia species are part of the normal human skin biota and can be isolated from different body areas, mainly those rich in sebaceous glands. Colonization is high during prepuberal and puberal for the increased activity of the sebaceous glands. Aims: Determine the colonization by Malassezia species in healthy skin of children and teenagers with HIV/AIDS. Methods: Samples were taken using imprint method with transparent adhesive tape, were taken from scalp, ear, chest, back, thigh, forearm and palm; were inoculated in Spondias dulcis medium. The species identification was performed according the instructions described by Guého et al, Tween diffusion test proposed by Guillot et al, catalase test, and the use of tryptophan as only source of nitrogen. Results: From a total of 80 children and teenagers, only 23 (28.75 percent) of them were isolated Malassezia. 10 (43.48 percent) were from males and 13 (56.52 percent) from females. Found only Malassezia sympodialis with a prevalence of 100 percent. Corresponding to the higher percentage of positivity the age group 4-7 years (56.52 percent). The predominant anatomical locations were: ear (25.5 percent) followed by chest (21.3 percent) and back (19.1 percent) respectively. Conclusions: In children with HIV / AIDS colonization pattern observed is the present of M. sympodialis.

Aislamiento e identificación fenotípica y genotípica de cepas de Malassezia spp. en pacientes con pitiriasis versicolor / Isolation and identification phenotypic and genotypic strains of Malassezia spp. in patients with pytiriasis versicolor

Antecedentes: Pitiriasis versicolor (PV) es una infección micótica superficial crónica de la piel, debido a la colonización del estrato córneo por Malassezia sp. Tradicionalmente M. furfur era considerada el agente causal de PV, hoy en día se ha demostrado que las especies de Malassezia más comunes cultivadas a partir de de lesiones de PV son M. globosa y M. sympodialis. Objetivos: Evaluar la epidemiología de la dermatomicosis PV, en pacientes de la ciudad de Talca, Chile. Metodología: En este estudio, 19 pacientes diagnosticados con PV fueron evaluados. Se realizó identificación fenotípica e identificación molecular por técnica de PCR-RFLP. Para esto, se diseñaron partidores que amplificaron una zona del 26S ADNr presente en todas las especies de Malassezia. Resultados: De un total de 19 pacientes con PV, 7 correspondieron a sexo masculino (36,8 por ciento) y 12 a sexo femenino (63,2 por ciento). Se obtuvieron 18 cepas, a partir de las pruebas fenotípicas fue posible identificar presuntivamente 11 especies de M. globosa (61,1 por ciento) y 7 especies de M. sympodialis (38,9 por ciento). Con los resultados obtenidos en la PCR-RFLP fue posible identificar 11 especies de M. globosa (61,1 por ciento) y 7 especies (38,9 por ciento) de M. sympodialis. Conclusiones: La especie identificada fenotípicamente y molecularmente en mayor proporción fue Malassezia globosa seguida de Malassezia sympodialis. Por lo que hay concordancia entre ambas técnicas de identificación. Este es el primer trabajo de investigación realizado en Talca, Chile, que identificó las especies de Malassezia spp. involucradas en PV, siendo un aporte al estudio de este cuadro clínico.

Background: Pytiriasis versicolor (PV) is a fungal infection of the skin due to the stratum corneum colonization by Malassezia sp. M. furfur traditionally was considered the etiological agent of PV but today it has been shown that M. globosa and M. sympodialis are the most common Malassezia species cultivated from PV lesions. Objective: To evaluate the epidemiological features of PV in patient of the Talca city, Chile. Method: In this study, 19 patients with diagnosis of PV were evaluated. Phenotypic and molecular identified were performed using PCR-RFLP. To do this, primers to amplify 26S ADNr secuence were designed. Result: From a total of 19 patients who presented PV, 7 were male (36.8 percent) and 12 female patients (63.2 percent). Eighteen strains were obtained, from the phenotypic tests, it was possible to presumably identify 11 species of M. globosa (61.1 percent) and 7 species of M. sympodialis (38.9 percent). With PCRRFLP results it was possible to identify 11 species of M. globosa (61.1 percent) and 7 species (38.9 percent) of M. sympodialis. Conclusion: The most commonly isolated species were Malassezia globosa followed by Malassezia sympodialis. So, there is agreement between both techniques of identification. This is the first research work carried out in Talca, Chile, which identified the species of Malassezia spp. Involved in PV, being a contribution to the clinical diagnosis.

Malassezia infections: a medical conundrum.

Malassezia yeasts have long been considered commensal fungi, unable to elicit significant damage. However, they have been associated with a diversity of cutaneous diseases, namely pityriasis versicolor, Malassezia folliculitis, seborrheic dermatitis, atopic dermatitis, psoriasis, and confluent and reticulate papillomatosis. Several hypotheses have been proposed to explain the pathogenic mechanisms of these fungi, but none have been confirmed. More recently, such organisms have been increasingly isolated from bloodstream infections raising serious concern about these fungi. Given the difficulty to culture these yeasts to proceed with speciation and antimicrobial susceptibility tests, such procedures are most often not performed and the cutaneous infections are treated empirically. The recurring nature of superficial skin infections and the potential threat of systemic infections raise the need of faster and more sensitive techniques to achieve isolation, identification, and antimicrobial susceptibility profile. This article reviews and discusses the latest available data concerning Malassezia infections and recent developments about diagnostic methods, virulence mechanisms, and susceptibility testing.

Malassezia skin diseases in humans.

Although Malassezia yeasts are a part of the normal microflora, under certain conditions they can cause superficial skin infection, such as pityriasis versicolor (PV) and Malassezia folliculitis. Moreover the yeasts of the genus Malassezia have been associated with seborrheic dermatitis and dandruff, atopic dermatitis, psoriasis, and, less commonly, with confluent and reticulated papillomatosis, onychomycosis, and transient acantholytic dermatosis. The study of the clinical role of Malassezia species has been surrounded by controversy due to the relative difficulty in isolation, cultivation, and identification. This review focuses on the clinical, mycologic, and immunologic aspects of the various skin diseases associated with Malassezia. Moreover, since there exists little information about the epidemiology and ecology of Malassezia species in the Italian population and the clinical significance of these species is not fully distinguished, we will report data about a study we carried out. The aim of our study was the isolation and the identification of Malassezia species in PV-affected skin and non-affected skin in patients with PV and in clinically healthy individuals without any Malassezia associated skin disease.

The Malassezia genus in skin and systemic diseases.

In the last 15 years, the genus Malassezia has been a topic of intense basic research on taxonomy, physiology, biochemistry, ecology, immunology, and metabolomics. Currently, the genus encompasses 14 species. The 1996 revision of the genus resulted in seven accepted taxa: M. furfur, M. pachydermatis, M. sympodialis, M. globosa, M. obtusa, M. restricta, and M. slooffiae. In the last decade, seven new taxa isolated from healthy and lesional human and animal skin have been accepted: M. dermatis, M. japonica, M. yamatoensis, M. nana, M. caprae, M. equina, and M. cuniculi. However, forthcoming multidisciplinary research is expected to show the etiopathological relationships between these new species and skin diseases. Hitherto, basic and clinical research has established etiological links between Malassezia yeasts, pityriasis versicolor, and sepsis of neonates and immunocompromised individuals. Their role in aggravating seborrheic dermatitis, dandruff, folliculitis, and onychomycosis, though often supported by histopathological evidence and favorable antifungal therapeutic outcomes, remains under investigation. A close association between skin and Malassezia IgE binding allergens in atopic eczema has been shown, while laboratory data support a role in psoriasis exacerbations. Finally, metabolomic research resulted in the proposal of a hypothesis on the contribution of Malassezia-synthesized aryl hydrocarbon receptor (AhR) ligands to basal cell carcinoma through UV radiation-induced carcinogenesis.

Dermatite seborreica / Seborrheic dermatitis

A dermatite seborreica é uma doença eritêmato-escamativa de caráter crônico-recidivante que acomete entre 1 e 3 por cento da população geral dos Estados Unidos. Possui dois picos de incidência - o primeiro, durante os três primeiros meses de vida, e o segundo, a partir da puberdade, atingindo seu ápice entre os 40 e 60 anos de idade. Os indivíduos HIV positivos têm maior prevalência da doença, que apresenta maior intensidade e tendência à refratariedade ao tratamento. Doenças neurológicas e outras doenças crônicas também estão associadas ao desenvolvimento da dermatite seborreica. Como mecanismo fisiopatogênico, reconhece-se que o fungo Malassezia sp., presente na pele de indivíduos suscetíveis, leve a uma irritação não-imunogênica a partir da produção de metabólitos à base de ácidos graxos insaturados deixados na superfície cutânea. Este artigo faz uma revisão da literatura sobre dermatite seborreica, com ênfase nos aspectos imunogenéticos, formas clínicas e tratamento.

Seborrheic dermatitis is a chronic relapsing erythematous scaly skin disease, the prevalence of which is around 1 to 3 percent of the general population in the United States. It has two incidence peaks, the first in the first three months of life and the second beginning at puberty and reaching its apex at 40 to 60 years of age. The prevalence of seborrheic dermatitis is higher in HIV-positive individuals and the condition tends to be more intense and refractory to treatment in these patients. Neurological disorders and other chronic diseases are also associated with the onset of seborrheic dermatitis. The currently accepted theory on the pathogenesis of this disease advocates that yeast of Malassezia spp., present on the skin surface of susceptible individuals, leads to a non-immunogenic irritation due to the production of unsaturated fatty acids deposited on the skin surface. This article provides a review of the literature on seborrheic dermatitis, focusing on immunogenetics, the clinical forms of the disease and its treatment.

Colonización de especies de malassezia en piel sana de niños en edad preescolar / Colonization of malassezia species on healthy skin of preschool children

Las levaduras del género Malassezia forman parte de la piel normal del hombre y otros vertebrados. La reciente descripción de nuevas especies para el género ha incentivado interés en el estudio de las mismas en diversos países, por lo tanto, es importante realizar investigaciones tendentes a obtener datos epidemiológicos de las especies en países tropicales como Venezuela. El estudio se realizó en piel sana de niños en edad preescolar (2 a 7 años) Las muestras fueron tomadas de diferentes áreas del cuerpo e inoculadas en el medio modificado de Dixon y Sabouraud Dextrosa Agar e incubadas a 32 °C. La identificación de las especies se realizó siguiendo las claves descritas por Guého y col. En la población estudiada se aislaron tres especies M. furfur, M. globosa y M. slooffiae. La especie predominante fue M. furfur con un 76,2% en todos los grupos etareos, seguida de M. globosa 16,7% y M. slooffiae 7,1% En relación a las localizaciones anatómicas M. furfur presentó un predominio en espalda (31,2%) seguida de pabellón auricular y pecho (21,9% respectivamente). M. globosa se aisló con mayor frecuencia de cuero cabelludo (71,4%) y M. slooffiae se observó en espalda (66,7%) y pabellón auricular (33,3%). Según las pruebas estadísticas aplicadas, no se encontraron diferencias significativas entre los grupos evaluados. Cabe destacar la importancia de continuar las investigaciones en otros grupos etarios, para establecer cuáles son las especies prevalentes en nuestra región y evaluar su potencial patógeno

Malassezia yeast forms part of the normal skin on man and other vertebrates. Recent descriptions of new species have stimulated interest in their study in diverse countries; it is important to conduct further research to collect epidemiological data about the species in tropical countries such as Venezuela. This study was made on healthy skins of preschool-age children (2 to 7 years). Samples were taken from different areas of the body, inoculated into a modified medium of Dixon and Sabouraud Agar and incubated at 32°C. Species identification was made following the code described by Guého and collaborators. In the population of children, three species were isolated: M furfur, M. globosa and M. slooffiae. The predominant species was M. furfur with 76.2% in all ages studied, followed by M globosa, 16.7%, and M. slooffiae, 7.1%. In relation to anatomical locations, M. furfur predominated on the back (31.2%), followed by the auricle (outer ear) and chest (21.9%), respectively. M globosa was most frequently isolated from the scalp (71.4%) and M. slooffiae was observed on the back (66.7%) and the auricle (33.3%). According to the statistical tests applied, there were no significant differences between the evaluated groups. It is important to continue this research with other age groups, to establish the prevalent species in this region and evaluate their pathogenic potential

Could Malassezia yeasts be implicated in skin carcinogenesis through the production of aryl-hydrocarbon receptor ligands?

UNLABELLED: Malassezia yeasts are found on the skin of all humans and many warm-blooded animals. In vitro they have the ability to synthesize potent ligands (indolo[3,2-b]carbazole, malassezin and indirubin) of the aryl-hydrocarbon receptor (AhR; synonym: dioxin receptor) when the sweat contained L-tryptophan is used as the single nitrogen source. The production of these AhR-ligands has been associated with pathogenic strains of a certain Malassezia species (Malassezia furfur) but recent evidence shows that this property is widely distributed in almost all currently known Malassezia species. AhR is associated with carcinogenesis and the potential connection of these ubiquitous skin symbionts, and putative pathogens, with skin neoplasia should be evaluated mainly focusing on mechanisms related to the distinctive ability of the yeast to produce potent AhR ligands. HYPOTHESIS: Synthesis of available pertinent data show a possible link between Malassezia produced AhR ligands and skin carcinogenesis, particularly of basal cell carcinoma (BCC). BCCs are almost exclusively observed in animal species colonized by Malassezia. In humans and animals there is overlapping in the skin regions colonized by this yeast and affected by BCC. The potent AhR ligands synthesized by pathogenic Malassezia strains could contribute to tumor promotion by: modification of the UV radiation carcinogenesis, alterations in the salvage/survival of initiated tumor cells, inhibition of cell senescence, interaction with vitamin D metabolism, promotion of immune tolerance and finally pro-carcinogenic modulation of cell cycle progression and apoptosis.

Malassezia virulence determinants.

PURPOSE OF REVIEW: Malassezia yeasts are associated with a number of dermatologic and systemic diseases in humans and animals. Pityriasis versicolor is amongst these diseases and represents one of the most common human skin diseases. Beyond that, the role of Malassezia yeasts in the pathogenesis of other skin diseases such as psoriasis, seborrheic dermatitis and confluent and reticulate papillomatosis is discussed but remains less clear. Clear pathogenetic mechanisms of the above-mentioned diseases are not known so far. The review presents new findings on virulence factors of Malassezia yeasts, shedding light on the pathogenesis of Malassezia-associated diseases. RECENT FINDINGS: Several virulence factors in Malassezia yeasts are known, based on their enzymatic lipolytic activity resulting in the production of distinct metabolites and special cell wall features. Recently, a secondary metabolic pathway possibly implicated in the pathogenesis of pityriasis versicolor was described. SUMMARY: The article presents virulence factors of Malassezia yeasts ranging from irritant metabolic byproducts to highly bioactive indole derivatives and attempts to clarify their pathogenic implications in the different diseases. Special emphasis is given to the pathogenesis of pityriasis versicolor, as it represents the disease wherein the causative relationship with Malassezia yeasts appears the most obvious.

Pitiriasis versicolor por Malassezia pachydermatis: caso clínico / Pityriasis versicolor caused by Malassezia pachydermatis: clinical case

Se presenta un caso clínico de pitiriasis versicolor por M. pachydermatis en una paciente de 11 años de edad, diagnosticado mediante clínica, morfofisiología y biología molecular. Malassezia pachydermatis es parte de la microbiota común de diversos mamíferos domésticos y animales salvajes. En éstos se reconoce como agente causal de dermatitis y otitis externa. En humanos se han descrito escasas infecciones ya sea superficiales como invasoras, lo que puede atribuirse a la difícil transmisión y adaptación a partir de los animales domésticos. Se comentan los aspectos biológicos y epidemiológicos de esta infección zoonótica.

A clinical case of pityriasis versicolor caused by M. pachydermatis in an 11 year old patient which was diagnosed by means of clinic, morphophysiology and molecular biology is presented. Malassezia pachydermatis is part of regular microbiota in several domestic mammals as well as wild animals. It is recognized as the causing agent of dermatitis and external otitis in the latter. As to human beings, superficial infections have rarely been given an invasive character what can be explained by the difficult transmission and adaptation coming from domestic animals. Biological and epidemiological aspects of this zoonotic infection are described.

Malassezia: is it a pulmonary pathogen in the stem cell transplant population?

Malassezia furfur is a yeast that can cause a variety of infections, most commonly in normal hosts, and also in immunocompromised hosts. This yeast typically colonizes the skin, and is the causative agent of tinea versicolor. However, in immunocompromised hosts, it can more commonly cause catheter-related fungemia or folliculitis. Pulmonary infections from Malassezia have not been commonly recognized. Unlike many other common opportunistic fungal infections in immunocompromised hosts, neutropenia and the use of broad-spectrum antibiotics do not appear to be significant risk factors for Malassezia infections in the stem cell transplant (SCT) population. Additionally, disseminated infection, despite fungemia, is uncommon. A series of patients who underwent SCT at the University of Minnesota between 2004 and 2006 were reviewed for the occurrence of suspected Malassezia infections in the post-transplant period. Four cases of possible pulmonary M. furfur infection were identified in our SCT recipients. The clinical characteristics of these patients, the infections, treatment, and outcome are described. In addition, we discuss the possible pathogenicity of this yeast in the pulmonary setting.

C-type lectin Mincle is an activating receptor for pathogenic fungus, Malassezia.

Mincle (also called as Clec4e and Clecsf9) is a C-type lectin receptor expressed in activated phagocytes. Recently, we have demonstrated that Mincle is an FcRgamma-associated activating receptor that senses damaged cells. To search an exogenous ligand(s), we screened pathogenic fungi using cell line expressing Mincle, FcRgamma, and NFAT-GFP reporter. We found that Mincle specifically recognizes the Malassezia species among 50 different fungal species tested. Malassezia is a pathogenic fungus that causes skin diseases, such as tinea versicolor and atopic dermatitis, and fatal sepsis. However, the specific receptor on host cells has not been identified. Mutation of the putative mannose-binding motif within C-type lectin domain of Mincle abrogated Malassezia recognition. Analyses of glycoconjugate microarray revealed that Mincle selectively binds to alpha-mannose but not mannan. Thus, Mincle may recognize specific geometry of alpha-mannosyl residues on Malassezia species and use this to distinguish them from other fungi. Malassezia activated macrophages to produce inflammatory cytokines/chemokines. To elucidate the physiological function of Mincle, Mincle-deficient mice were established. Malassezia-induced cytokine/chemokine production by macrophages from Mincle(-/-) mice was significantly impaired. In vivo inflammatory responses against Malassezia was also impaired in Mincle(-/-) mice. These results indicate that Mincle is the first specific receptor for Malassezia species to be reported and plays a crucial role in immune responses to this fungus.

Actividad lipasa de especies de Malassezia aisladas en pacientes sanos y con lesiones dérmicas / Lipase activity of Malassezia species isolated from healthy patients and having dermic lesions

Las levaduras del género Malassezia forman parte de la micro biota normal de piel humana y animal. Excepto M. pachydermatis, todas las especies de este género son lipodependientes. Bajo ciertos factores, Malassezia se asocia como agente etiológico en diversas afecciones dérmicas. Uno de los principales factores de virulencia de estas levaduras es su actividad de lipasa (AL). El objetivo de este trabajo fue introducir modificaciones a las técnicas de determinación de la actividad lipasa (AL) para su aplicación en levaduras lipodependientes y estudiar la AL en cepas de Malassezia aisladas de personas con piel sana y de pacientes con pitiriasis versicolor (PV), dermatitis seborreica (DS) y psoriasis (PS). Se estudiaron 94 cepas aisladas de 34 pacientes con lesiones de PV, 20 con DS, 7 con PS y 33 cepas de personas con piel sana. Las modificaciones planteadas a la técnica, que incluyeron variación del medio de cultivo y tiempos de incubación, permitieron la determinación semi cuantitativa de la AL con resultados claros y definidos. El 88,23 por ciento de las cepas presentó AL. No se obtuvieron diferencias estadísticamente significativas al comparar la AL entre las cepas de pacientes con afecciones de piel y las cepas aisladas de personas sanas. La producción de lipasas de las especies de Malassezia en orden decreciente fue: M. sympodialis, M. slooffiae, M. furfur, M. globosa, M. restricta. M. globosa y M. furfur fueron las especies en que se observaron mayor cantidad de cepas no productoras de AL y cepas con gran variabilidad en la medida de AL.

Yeasts of the genus Malassezia are part of the regular microbiota in human and animal skin. Except for M. pachydermatis, all the species of this genus are lipodependent. Malassezia, under certain factors, is associated as an etiological agent in diverse dermic affections. One of the main virulence factors of these yeasts is their lipase activity (LA). The objective of this research was to introduce some changes in the techniques adopted to determine the lipase activity (LA) in order to apply them to lipodependent yeasts and to study likewise the LA in Malassezia strains isolated from healthy skin people and patients diagnosed with pitiriasis versicolor (VP), greasy dermatitis (GD) and psoriasis ( PS). Ninety four strains isolated from 34 patients having VP lesions, 20 with GD, 7 with PS and 33 strains from healthy skin people. Changes suggested to the technique involved a variation in the medium of culture as well as in the time of incubation what resulted in the semiquantitative determination of the LA together with clear and precise results. The presence of LA was observed in of 88.23 percent strains. The comparison of the LA among strains of patients bearing injured skin and those isolated from healthy skin did not show any significant statistical difference. The production of lipasae from Malassezia species were in decreasing order: M.sympodialis, M. slooffiae, M.furfur,M.globosa and M.restricta. M. globosa and M. furfur were the species that revealed the highest number of non producting LA strains as well as strains with the highest variability in the degree of LA.