花斑癣、马拉色菌毛囊炎、脂溢性皮炎马拉色菌诱发因素分析

目的调查昆明地区花斑癣、马拉色菌毛囊炎、脂溢性皮炎马拉色菌诱发因素,并比较三种疾病的诱发因素有无差异。方法收集花斑癣、马拉色菌毛囊炎、脂溢性皮炎(头皮屑)的病例,用自制的调查表对入选病例进行诱发因素调查,比较诱发因素在三种疾病间有无差异。结果共收集158例病例,男104例,女54例,平均年龄29.4岁,多汗、油性皮肤患者所占比例均超过60%,系统或局部使用糖皮质激素是马拉色菌毛囊炎的危险因素。结论马拉色菌感染好发于男性青壮年,多汗者易发生花斑癣,油性皮肤及使用糖皮质激素易发生马拉色菌毛囊炎。     

Skin diseases associated with Malassezia species

The yeasts of the genus Malassezia have been associated with a number of diseases affecting the human skin, such as pityriasis versicolor, Malassezia (Pityrosporum) folliculitis, seborrheic dermatitis and dandruff, atopic dermatitis, psoriasis, and--less commonly--with other dermatologic disorders such as confluent and reticulated papillomatosis, onychomycosis, and transient acantholytic dermatosis. Although Malassezia yeasts are a part of the normal microflora, under certain conditions they can cause superficial skin infection. The study of the clinical role of Malassezia species has been surrounded by controversy because of their fastidious nature in vitro, and relative difficulty in isolation, cultivation, and identification. Many studies have been published in the past few years after the taxonomic revision carried out in 1996 in which 7 species were recognized. Two new species have been recently described, one of which has been isolated from patients with atopic dermatitis. This review focuses on the clinical, mycologic, and immunologic aspects of the various skin diseases associated with Malassezia. It also highlights the importance of individual Malassezia species in the different dermatologic disorders related to these yeasts.     

Cell-mediated immunity to Malassezia furfur in patients with seborrhoeic dermatitis and pityriasis versicolor

The lymphocyte transformation response to Malassezia furfur, Candida albicans, phytohaemagglutinin, concanavlin A and tuberculin purified protein derivative of 12 patients with pityriasis versicolor, 15 patients with seborrhoeic dermatitis and matched controls, was studied. Patients with pityriasis versicolor showed a significantly lower response to M. furfur than patients with seborrhoeic dermatitis and controls.     

Pityriasis versicolor alba

Pityriasis versicolor alba is a hypopigmented or depigmented variant of pityriasis versicolor characterized by maculous, partly pityriasiform, scaly depigmented lesions occurring particularly in seborrhoeic areas. Long-persisting hypopigmentation after healing of the pityriasis versicolor was first described by Gudden in 1853. Hypopigmentation and depigmentation were later differentiated as an independent variant of the disease. In 1848, Eichstedt recognized the pathogen-related character of pityriasis versicolor in its hyperpigmented form. Today it is generally accepted that the disease is caused by yeasts of the genus Malassezia, of which nine species are differentiated. It is controversial whether a single species is responsible for the disease. The pathogenesis of depigmentation has not been established. A screening effect by the scale layer as well as toxic effects on pigment synthesis by fungal metabolites have been discussed. With regard to the second mechanism, the newly discovered tryptophan-derived metabolites of M. furfur might be significant. Evidence-based data concerning the therapy of pityriasis versicolor alba do not exist. According to current recommendations, pityriasis versicolor should be rapidly treated with antimycotics, followed by ultraviolet therapy to induce maturation of existent melanosomes and accelerate repigmentation. However, depigmented lesions are difficult to improve by ultraviolet therapy.     

Cutaneous Malassezia flora in atopic dermatitis differs between adults and children

BACKGROUND: Malassezia species are suspected to be involved in the development of skin lesions in atopic dermatitis (AD) when the response of adult AD to anti-inflammatory treatments is poor. However, a comparative analysis of Malassezia flora between adults and children with AD has not been performed. OBJECTIVES: To compare the cutaneous Malassezia flora between adults and children with AD. METHODS: Scale samples were collected from skin lesions of 58 patients with AD in the head and neck regions (28 males and 30 females; 31 children and 27 adults), and fungal DNA was extracted from the samples directly. The number and identities of the Malassezia species were analysed with high accuracy using a polymerase chain reaction-based culture-independent method. The in vivo level of anti-Malassezia IgE antibody was also assayed. RESULTS: Malassezia restricta was the predominant species in the children with AD, while both M. restricta and M. globosa predominated in the adults. The adults showed increased sensitization in terms of anti-Malassezia-specific IgE responses in the sera to both M. globosa and M. restricta in comparison with the children. CONCLUSIONS: The cutaneous Malassezia flora differs significantly between the two age groups.     

Atopic dermatitis in adults: does it disappear with age?

There is limited knowledge of the prognosis in adult atopic dermatitis. We previously published a long-term follow-up questionnaire study of adults with atopic dermatitis. This study is a clinical examination of 79 adults (mean age 57 years) recruited 3 years after that study. Most patients (68%) still reported that they had atopic dermatitis and 53% had ongoing eczema at examination, mainly located on the head and neck. Severity was mainly mild to moderate, but 12% had severe atopic dermatitis. IgE antibodies to Malassezia (m70) were more common in patients with ongoing atopic dermatitis, while positive Malassezia culture was seen mainly in patients with no ongoing atopic dermatitis. M. obtusa and M. globosa were the most commonly cultured Malassezia species. In conclusion, considering increased prevalence of atopic dermatitis in children in recent decades and the fact that atopic dermatitis in most adults continues for many years, we should expect to see more adults with atopic dermatitis in the future.     

Malassezia yeasts and their significance in dermatology

Yeasts of the genus Malassezia belong to the normal microflora of the human skin. In addition they are known to cause a variety of skin diseases; the most frequent of which is pityriasis versicolor. Malassezia yeasts are also thought to be associated with seborrheic dermatitis, dandruff and Malassezia folliculitis. Recently the significance of Malassezia yeasts as a trigger factor for atopic dermatitis of the head and neck region has been pointed out. The role of the Malassezia yeasts in these different diseases has been controversial in the past and remains an issue because of difficulties in isolation, culture and differentiation of the organism. Thanks to molecular techniques, 10 species can actually be differentiated. The article presents the different Malassezia-associated diseases, their clinical picture, diagnosis and appropriate therapy. In addition the speciation of Malassezia is reviewed.     

Malassezia-Hefen und ihre Bedeutung in der Dermatologie

Yeasts of the genus Malassezia belong to the normal microflora of the human skin. In addition they are known to cause a variety of skin diseases; the most frequent of which is pityriasis versicolor. Malassezia yeasts are also thought to be associated with seborrheic dermatitis, dandruff and Malassezia folliculitis. Recently the significance of Malassezia yeasts as a trigger factor for atopic dermatitis of the head and neck region has been pointed out. The role of the Malassezia yeasts in these different diseases has been controversial in the past and remains an issue because of difficulties in isolation, culture and differentiation of the organism. Thanks to molecular techniques, 10 species can actually be differentiated. The article presents the different Malassezia-associated diseases, their clinical picture, diagnosis and appropriate therapy. In addition the speciation of Malassezia is reviewed.     

马拉色菌相关婴儿皮肤病

马拉色菌是人皮肤表面的常驻真菌，能引起婴儿花斑癣，并与婴儿脂溢性皮炎、婴儿特应性皮炎、新生儿头部脓疱病、婴儿及新生儿痤疮的发病相关。这种相关性主要表现在皮损处能检出马拉色菌，且抗真菌治疗有效，在婴儿特应性皮炎的发病中，主要作为抗原。由于婴儿和新生儿的皮肤屏障功能、机体免疫功能等尚不成熟，在患该类疾病时临床表现不典型，较成人有差异，治疗以外用药物为主。     

Humoral immunity to Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrheic dermatitis and controls

Abstract This study examined the humoral immune responses to Malassezia furfur serovars A, B and C of 10 patients with pityriasis versicolor, 10 patients with seborrheic dermatitis and 20 age- and sex-matched controls. A transferable solid-phase ELISA was used to determine titres of total Igs, IgM, IgA and IgG specific to M. furfur serovars A, B and C. The results demonstrated that patients with seborrheic dermatitis had a significantly higher litre of total Igs to serovar A than patients with pityriasis versicolor; and that patients with seborrheic dermatitis had a significantly higher litre of IgA to serovar C than patients with pityriasis versicolor. The litres of total Igs for controls and patienls with seborrheic dermatitis were significantly lower to serovar B than to serovar C. A modified TSP ELISA was used to determine the titres of the IgG subclasses. Titres of IgG _1,3,4 to serovar B were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients and litres of IgG₃, to serovar A were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients. However, despite the differences between the patient groups, none of these results was significantly different to those of controls. Thus, this study did not demonstrate any differences in humoral immunity of patients suffering from Malassezia-associated dermatoses when compared to normal controls. These results may suggest that the humoral immune response to M. furfur is not related to the pathogenesis of Malassezia-associated dermatoses, but simply to the carriage of M. furfur on the skin.     

The carriage of Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrhoeic dermatitis and controls

The aetiological role of Malassezia furfur in various dermatoses is controversial. The role of the three serovars of M. furfur in Malassezia-associated diseases has not been investigated. This study measured population densities of M. furfur serovars A. Band C. propionibacteria and Micrococcaceae on the chest, back, forehead, left and right cheeks of 10 patients with pityriasis versicolor, and 10 age- and sexmatched controls: and 10 patients with seborrhoeic dermatitis, and 10 age- and sex-matched controls. The population densities of M. furfur. propionibacteria and Micrococcaceae did not vary at a given site between patients and the corresponding control subjects. Malassezia furfu serovar A was found to be the predominant isolate on the chest and back of all four groups. but there was no difference in the distribution of serovars on the forehead and cheeks. No serovar was specifically associated with lesional skin in either disease. Thus, this data indicated that there was no difference in either the total population density of M. furfur or the distribution of serovars on lesional skin compared with control skin in either pityriasis versicolor or seborrhoeic dermatitis.     

Pityriasis versicolor

Pityriasis versicolor is a common superficial fungal infection of the skin. It is caused by Malassezia spp., which are normal human saprophytes. Under certain conditions, both exogenous and endogenous, the fungus can convert from a yeast to a pathogenic mycelial form. This alteration results in mild inflammation of the skin, and in characteristic clinical and histological changes. The taxonomy of Malassezia spp. has recently been modified to include six obligatorily lipophilic species, all of which can be found on human skin, plus one non-obligatorily lipophilic species, which only rarely colonizes human hosts. LEARNING OBJECTIVES: At the conclusion of this learning activity, participants should be aware of the role of Malassezia in the development of pityriasis versicolor, the clinical and histological changes arising from this dermatosis, and the diagnosis and treatment of this disorder.     

Molecular analysis of Malassezia microflora in seborrheic dermatitis patients: comparison with other diseases and healthy subjects

Malassezia species colonize the skin of normal and various pathological conditions including pityriasis versicolor (PV), seborrhoeic dermatitis (SD) and atopic dermatitis (AD). To elucidate the pathogenic role of Malassezia species in SD, Malassezia microflora of 31 Japanese SD patients was analyzed using a PCR-based, culture-independent method. Nested PCR assay using the primers in the rRNA gene indicated that the major Malassezia species in SD were M. globosa and M. restricta, found in 93 and 74% of the patients, respectively. The detection rate and number of each species varied similarly in SD, PV and healthy subjects (HSs), whereas AD showed higher values. Real-time PCR assay showed that the lesional skin harbored approximately three times the population of genus Malassezia found in nonlesional skin (P<0.05), and that M. restricta is a significantly more common species than M. globosa in SD (P<0.005). Genotypic analysis of the rRNA gene showed that the M. globosa and M. restricta from SD patients fell into specific clusters, and could be distinguished from those collected from HSs, but not from those colleted from AD patients. Our results indicate that certain strains of M. restricta occur in the lesional skin of SD patients.     

Pityriasis (Tinea) Versicolor in Infancy

Pityriasis (tinea) versicolor is a common disorder of adults. We cared for five infants (four males and one female) with the disease. Diagnosis was confirmed by potassium hydroxide preparation demonstrating the filaments of Malassezia furfur and/or Pityrosporum orbiculare, the yeast form. Three patients had lesions in the neonatal period. The mother of one baby had pityriasis versicolor. Two patients were siblings. One baby had associated atopic dermatitis and two had a positive family history of atopy.     

PITYRIASIS VERSICOLOR: A CLINICOMYCOLOGICAL AND EPIDEMIOLOGICAL STUDY FROM A TERTIARY CARE HOSPITAL

Background:

Pityriasis versicolor is a mild, chronic, usually asymptomatic superficial fungal infection of the stratum corneum, caused by Malassezia yeasts. The purpose of the present study is to assess the clinical profile of a group of patients with pityriasis versicolor and to find out the epidemiological characteristics in this part of India as well as any association, if any, with other diseases.

Materials and Methods:

For this purpose, 110 consecutive patients of pityriasis versicolor were evaluated clinically and diagnosis was confirmed mycologically at a tertiary care hospital in Kolkata. All data were recorded in a predesigned, pretested semi-structured schedule. The total duration of study period was 12 months.

Results:

Majority of the patients were young adults. Most of the patients were asymptomatic. There is prominent seasonal variation of the patients with a peak in August and September months. Most of the lesions were hypopigmented scaly macules and were KOH positive. Most commonly involved sites were chest, face and back. Seborrheic dermatitis sometimes coexisted with pityriasis versicolor and a number of patients also had diabetes mellitus and immunosuppressive conditions.

Conclusions:

Overall, the clinicomycological and epidemiological profile of pityriasis versicolor infection as observed in a tertiary care setting in eastern India does not differ significantly from those observed by previous workers elsewhere.     

In vitro activity of R126638 and ketoconazole against Malassezia species

The in vitro activity of a new triazole R126638 against Malassezia yeasts was compared with that of ketoconazole. With the agar dilution technique, minimal inhibitory concentrations were lower for R126638 compared with ketoconazole against Malassezia globosa, M. obtusa, M. slooffiae, M. restricta and two strains of M. sympodialis. On human stratum corneum in vitro, both R126638 and ketoconazole were very effective in reducing the production of hyphae from 15% to 1% with R126638 and to 2% with ketoconazole. Scanning electron microscopy did not reveal obvious surface differences between untreated cultures and cultures exposed to ketoconazole or R126638 in the concentration range 0.01-1 microg/ml. However, transmission electron microscopy showed partial to complete necrosis of the cytoplasmic organelles of Malassezia yeasts. The combined scanning electron microscopy and transmission electron microscopy findings confirm earlier observations of the "mummifying" effect of azoles against Malassezia spp. In conclusion, R126638 is an interesting new triazole with high activity against the Malassezia yeasts, which are involved in pityriasis versicolor and seborrhoeic dermatitis.     

马拉色菌属的研究进展

马拉色菌是一种寄生于人和动物正常皮肤表面的真菌,可导致机会感染而引起各种马拉色菌属相关疾病。马拉色菌的致病机制主要是分解脂质,导致角质形成细胞形态学改变和细胞凋亡。马拉色菌可引起花斑癣、脂溢性皮炎、马拉色菌毛囊炎等,在特应性皮炎中也起到变应原的作用。对于这些疾病的治疗可使用抗真菌药物。     

IgE antibodies to Malassezia furfur, M. sympodialis and Pityrosporum orbiculare in patients with atopic dermatitis, seborrheic eczema or pityriasis versicolor, and identification of respective allergens

Malassezia yeasts may be a trigger factor for atopic dermatitis. Following the recent reclassification of the genus, the presence of specific IgE antibodies was examined in the sera of patients with atopic dermatitis (n = 223), pityriasis versicolor (n = 83), seborrheic eczema (n = 50) and hymenoptera allergy (n = 39) and in controls without skin diseases (n = 50). In addition to using the commercially available radioallergosorbent test (RAST) for Pityrosporum orbiculare couplings were also made against the reference strains for M. furfur and M. sympodialis. To characterize the specificity and molecular weight of corresponding epitopes identical material was used for production of an immunoblot. Despite high total levels of IgE, controls and patients with pityriasis versicolor showed no specific IgE antibodies. Six patients (12%) with seborrheic eczema were positive while 78 patients (35%) with atopic dermatitis had specific IgE antibodies in higher RAST classes that differed between the Malassezia species. The molecular weights of the main antigens of M. sympodialis and M. furfur were determined to be 15, 22, 30, 37, 40, 58, 79, 92, 99 and 124 kDa and 15, 25, 27, 43, 58, 92, 99 and 107 kDa, respectively. Evaluated according to the location of their disease, patients with head and neck lesions most frequently showed Malassezia-specific IgE antibodies. However, there were differences between the Malassezia species tested, the previously used strain P. orbiculare being assignable to the species M. sympodialis.     

Distribution of Malassezia species in pityriasis versicolor and seborrhoeic dermatitis in Greece. Typing of the major pityriasis versicolor isolate M. globosa

BACKGROUND: The expansion of the genus Malassezia has generated interest in the epidemiological investigation of the distribution of new species in a range of dermatoses, on which variable results have been reported from different geographical regions. No data are thus far available from South-east Europe (Greece). OBJECTIVES: To study the distribution of Malassezia species in pityriasis versicolor (PV) and seborrhoeic dermatitis (SD) and to investigate whether polymorphisms in the internal transcribed spacer (ITS) 1 region facilitate detection of M. globosa and M. sympodialis subtypes. METHODS: In total, 109 patients with PV and SD and positive Malassezia cultures were included in the study. Age, gender, primary/recurrent episode, disease extent and clinical form of PV were recorded. ITS 1 polymorphisms of M. globosa and M. sympodialis type and clinical strains were investigated by polymerase chain reaction (PCR)-single-strand conformational polymorphism (SSCP) analysis. RESULTS: Malassezia globosa was the prevalent species isolated from PV and SD either alone (77% and 39%, respectively) or in combination (13% and 18%, respectively) with other Malassezia species. The pigmented form of PV was strongly correlated with the female gender. PCR-SSCP differentiated five subgroups of M. globosa with one being associated with extensive clinical disease. All M. sympodialis isolates displayed a homogeneous ITS 1 PCR-SSCP profile. CONCLUSIONS: Malassezia species isolation rates were in agreement with those reported from South-west Europe. PCR-SSCP of the ITS 1 is useful for highlighting prospective clinical implications of M. globosa subtypes.     

The role of Malassezia in atopic dermatitis affecting the head and neck of adults

Atopic dermatitis is a common chronic skin condition. A subset of patients with head and neck dermatitis may have a reaction to Malassezia flora fueling their disease. Although there are no documented differences in Malassezia species colonization, patients with head and neck atopic dermatitis are more likely to have positive skin prick test results and Malassezia-specific IgE compared with healthy control subjects and patients with atopy without head and neck dermatitis. There is no clear relationship with atopy patch testing. The reaction to Malassezia is likely related to both humoral- and cell-mediated immunity. Clinically, Malassezia allergy may be suspected in patients with atopic dermatitis and: (1) head and neck lesions; (2) exacerbations during adolescence or young adulthood; (3) severe lesions recalcitrant to conventional therapy; and (4) other atopic diseases. There is literature to suggest that these patients will benefit from a 1- to 2-month course of daily itraconazole or ketoconazole followed by long-term weekly treatment.