Taxonomy of Malassezia furfur: state of the art

Malassezia furfur is a lipophilic yeast considered as a normal component of the human skin flora. Apart from pityriasis versicolor, M. furfur has been linked to several skin diseases such as seborrheic dermatitis, folliculitis or atopic dermatitis. Moreover, these yeasts have been reported as agent of invasive human diseases including pneumonia, catheter-associated sepsis and peritonitis. The existence of morphological, serological, metabolical, biochemical and karyotipical differences has been described among isolates of these yeasts. These observations gave arguments for a possible intraspecific division, and this hypothesis has been confirmed by the existence of six species within the formerly called M. furfur (lipid-dependent Malassezia strains): M. furfur, Malassezia sympodialis, Malassezia globosa, Malassezia obtusa, Malassezia restricta and Malassezia slooffiae.     

Species of Malassezia associated with various dermatoses and healthy skin in the Mexican population

At the present, eight Malassezia species have been described and their distribution in normal skin and in several skin diseases appears variable. The aim of the present study was to determine the frequency and distribution of Malassezia species in patients with psoriasis, seborrhoeic dermatitis and pityriasis versicolor attended in a Hospital from Mexico City, in addition to a healthy individual group. Scales of abnormal and healthy skin were grown in modified Dixon agar and the species identification was performed by macroscopic and microscopic features; by catalase and urease reaction; growth at 32, 37 and 40 degrees C; and Tween 20, 40, 60 and 80 assimilation. The cultures from 63 persons were included: forty six patients (20 psoriasis, 15 seborrhoeic dermatitis, 11 pityriasis versicolor) and 17 healthy individuals (external auditory canal). A total of 96 isolates were obtained. The more frequently isolated species were: M. sympodialis (38.2%) and M. furfur (26.5%) in psoriasis; M. sympodialis (38.5%) and M. slooffiae (34.6%) in seborrhoeic dermatitis; M. globosa (46.7%) and M. sympodialis (26.7%) in pityriasis versicolor; and M. restricta (47.6%) and M. globosa (23.8%) in normal skin. The number of isolates, the species diversity and association were higher in the patients group than in the healthy individuals group.     

Concordance between phenotypical features and PCR-REA for the identification of Malassezia spp

The genus Malassezia has been recently revised and nowadays includes 11 species that cannot always be differentiated from each other by physiological and morphological tests. This study was aimed to evaluate the correlation between a molecular method and conventional phenotypic features in the identification of Malassezia spp. To achieve this aim, 92 Argentinean clinical strains isolated between 2001 and 2005 were analyzed along with three reference strains (Malassezia furfur CBS 7019, Malassezia sympodialis CBS 7222 and Malassezia slooffiae CBS 7956). By using PCR and restriction enzyme analysis with three different DNA endonucleases (PCR-REA), the molecular method consistently identified all three reference strains and all 92 clinical isolates as follows: 63 M. sympodialis, 18 M. furfur, 10 Malassezia globosa and one Malassezia obtusa. Phenotypic studies undentified 85 clinical isolates and two of the reference strains (total agreement > 91%). In particular for M. sympodialis, M. furfur and M. globosa, the species more frequently involved in human pathology, the agreement ranged between 84 and 96%. This result suggests that phenotypic studies are suitable for the presumptive identification of important Malassezia species in the clinical medical mycology laboratories where molecular methodologies are not available.     

Detection and quantification of specific IgE antibodies against eight Malassezia species in sera of patients with atopic dermatitis by using an enzyme-linked immunosorbent assay

The lipophilic yeast Malassezia, a member of the cutaneous microflora, is an exacerbating factor in atopic dermatitis (AD). Of the 11 currently recognized species, M. globosa and M. restricta are found to frequently colonize the skin of AD patients. In this study, we attempted to quantify specific IgE antibodies against eight Malassezia species, namely, M. dermatitis, M. furfur, M. globosa, M. obtusa, M. pachydermatis, M. slooffiae, M. sympodialis, and M. restricta, in sera from AD patients by using an enzyme-linked immunosorbent assay (ELISA). The specific IgE value against M. restricta was greater than those against other Malassezia species. Competitive ELISA inhibition tests revealed that M. restricta contained species specific as well as shared antigens. Therefore, M. restricta could be considered as a candidate diagnostic antigen for detecting anti-Malassezia IgE in sera from AD patients.     

马拉色菌相关人群及正常人群耳耵聍中马拉色菌带菌情况的调查

目的调查马拉色菌相关人群及正常人群耳耵聍中马拉色菌带菌情况。方法用结晶紫染色法对96例被调查人群耳耵聍进行马拉色菌检测,同时作培养,并以标准株作对照,用生理生化方法将耵聍中分离到的79株马拉色菌进行分类。结果马拉色菌相关人群耳耵聍中马拉色菌的直接检出率为91．84％（45／49）,培养阳性率为81．63％（40／49）,其中厚皮马拉色菌8株（16．33％）,合轴马拉色菌10株（20．41％）,糠秕马拉色菌22株（44．90％）。正常人群耳耵聍马拉色菌直接检出率为89．36％（42／47）,培养阳性率为78．72％（37／47）,其中厚皮马拉色菌5株（10．64％）,合轴马拉色菌8株（17．02％）,糠秕马拉色菌23株（48．93％）,斯洛菲马拉色菌1株（2．13％）。结论马拉色菌为正常人群及马拉色菌相关人群外耳道正常菌群,两组人群中马拉色菌的分离率和菌种分布无显著性差异。     

正常人耵聍中马拉色菌菌种构成研究

目的研究正常人耵聍中马拉色菌菌种构成及同一宿主耵聍中菌种是否一致。方法采集45名健康志愿者双侧耵聍,0.1%曲拉通X-100溶解稀释后接种于含菜籽油培养基,生化及形态学方法鉴定到种,同时提取菌种DNA,用真菌通用引物ITS1/ITS4做PCR扩增并测序鉴定。结果有44例(97.78%)双侧耵聍中均培养出马拉色菌(共分离出88株菌),菌种构成:糠粃马拉色菌29株(32.95%)、斯洛菲马拉色菌23株(26.14%)、合轴马拉色菌18株(20.45%)、球形马拉色菌11株(12.50%)、限制性马拉色菌7株(7.95%)。44例(88株菌)中双侧耵聍菌种相同者有38例(76株菌)(一致率86.36%)。结论正常人耵聍中马拉色菌菌种分布较广,主要菌种为糠秕马拉色菌。同一宿主双侧耵聍中马拉色菌菌种具有一定的一致性。     

Occurrence of Malassezia species in healthy and dermatologically diseased dogs

The presence of Malassezia spp. yeasts was investigated in dermatological specimens of 224 dogs, 164 dermatologically diseased and 60 normal dogs. Subjects included in the study were of different breed, age, sex and habitat. Malassezia spp. positive cultures were obtained in 142 (63.4%) specimens: 67.6% from dermatologically diseased subjects and 51.6% from healthy dogs. Malassezia pachydermatis, either as a pure culture or in association with lipid-dependent species, was identified in 138 (97%) specimens. Malassezia furfur was identified in 69 (48.6%) specimens and was associated with other Malassezia species in 68 dogs, as a pure culture in one subject: at the best of our knowledge, this species was identified before as the sole species from canine dermatitis. Malassezia sympodialis was identified in 11 (7.7%) specimens, always in association with other species: it was never isolated from kennel dogs. Statistical analysis of data showed a very significant difference (P < 0.01) in the prevalence of isolation of Malassezia spp. between animals with and without dermatological signs, and in the distribution of cultural burden between diseased and healthy dogs. A statistically significant difference (P<0.05) was also detected in the group of animals between 1- and 5-years of age. No significant difference was found between male and female dogs.     

南海海军部队特发性瘙痒症患者皮肤马拉色菌定植调查

目的研究南海海军部队特发性皮肤瘙痒症患者皮肤马拉色菌的检出以及菌种的构成,探讨马拉色菌与特发性瘙痒症之间的相关性。方法对采自56例特发性瘙痒症患者与50例健康者的鳞屑标本进行真菌学镜检及采用菜子油培养基培养,根据菌落形态和生理生化特点进行菌种鉴定。结果观察组与对照组镜检阳性率分别为74．10％和72．00％,X2=0．344,P〉0．05两者比较无统计学意义。而镜检马拉色菌孢子密度Ⅲ级以上（每10个高倍视野≥50个者）,观察组与对照组分别为74．70％和38．89％,X2=20．30,P〈0．01。两者统计学比较差异有显著性意义。观察组168份标本共分离出143株马拉色菌,阳性率85．12％。其中合轴马拉色菌97株（67．83％）,球形马拉色菌26株（18．18％）,糠秕马拉色菌19株（13．29％）,钝形马拉色菌1株（0．70％）。对照组分离出马拉色菌107株,阳性率71．33％;其中糠秕马拉色菌55株（51．40％）,合轴马拉色菌33株（30．84％）,球形马拉色菌14株（13．08％）,钝形马拉色菌5株（4．67％）。菌种检出率和菌种构成差异均有显著性（X2=2．99,P〈0．01和7。X2=51.16,P〈0．01）。结论南海海军部队特发性瘙痒症患者皮肤马拉色菌载量较正常人高,其优势菌是合轴马拉色菌。     

Chitin synthase 2 gene sequence of Malassezia species.

Nucleotide sequences of the chitin synthase 2 (CHS2) gene of seven species, Malassezia furfur, M. globosa, M. obtusa, M. pachydermatis, M. restricta, M. slooffiae and M. sympodialis, were analyzed for their phylogenetic relationship. About 620-bp genomic DNA fragments of the CHS2 gene were amplified from these Malassezia species by polymerase chain reaction (PCR) and sequenced. The CHS2 nucleotide sequences of these Malassezia species showed more than 95% similarity between the species. A phylogenetic analysis of the nucleotide sequences of CHS2 gene fragments of seven Malassezia species revealed that the species were genetically distinct from each other.     

Quantitative analysis of cutaneous malassezia in atopic dermatitis patients using real-time PCR

We quantified the cutaneous Malassezia in patients with atopic dermatitis using a real-time PCR assay. Seven to 12 times more Malassezia colonized the head and neck compared to the trunk or limbs, and the species M. globosa and M. restricta accounted for approximately 80% of all Malassezia colonization at any body site.     

Functional expression and characterization of CYP51 from dandruff-causing Malassezia globosa

Malassezia globosa is one of the most common yeasts to cause various human skin diseases including dandruff and seborrheic dermatitis. Genomic analysis of M. globosa revealed four putative cytochrome P450 (CYP) enzymes. Here, we report the purification and characterization of recombinant CYP51, a putative lanosterol 14α-demethylase, from M. globosa. The M. globosa CYP51 was expressed heterologously in Escherichia coli, followed by purification. Purified CYP51 showed a typical reduced CO-difference spectrum of P450, with a maximum absorption at 447?nm. Purified CYP51 exhibited tight binding to azole antifungal agents such as ketoconazole, econazole, fluconazole, or itraconazole, with K(d) values around 0.26-0.84?μM, which suggests that CYP51 is an orthologous target for antifungal agents in the M. globosa. In addition, three mutations (Y127F, A169S, and K176N) in the amino acid sequence of M. globosa CYP51 were identified in one of the azole-resistant strains. Homology modeling of M. globosa CYP51 suggested that the Y127F mutation may influence the resistance to azoles by blocking substrate access channels. Taken together, functional expression and characterization of the CYP51 enzyme can provide a fundamental basis for a specific antifungal drug design for dandruff caused by M. globosa.     

东南亚青年人群中马拉色菌菌种构成分析

目的：研究部分东南亚国家青年人群中马拉色菌菌种构成。方法采集285名青年人（分别来源于中国、尼泊尔、印度、巴基斯坦）面部正常皮肤及皮损区标本,接种于 Leeming ＆amp; Notman 培养基后进行培养分离,生化及形态学方法鉴定到种。结果共分离出8个菌种,共计501株马拉色菌,以球形马拉色菌为主,占40.5℅（203/501）,其次为合轴马拉色菌19.0℅（95/501）、糠秕马拉色菌16.0℅（80/501）、限制马拉色菌11.0℅（55/501）、斯洛菲马拉色菌6.2℅（31/501）等。各国家间未见明显的地理学差异。结论东南亚地区青年正常人群及马拉色菌相关疾病患者中的主要菌种为球形马拉色菌。     

Recent developments in the immunology and biology of Malassezia species

Malassezia spp. are members of the normal cutaneous flora, but are also associated with several cutaneous diseases. Recent studies of the interaction of Malassezia spp. with melanocytes, fibroblasts, keratinocytes and dendritic cells have highlighted their potential to modulate the immune response directed against them. In normal skin they may downregulate the inflammatory response, allowing them to live as commensals. In contrast, in atopic/eczema dermatitis syndrome and psoriasis, they may elicit an inflammatory response that contributes to the maintenance of lesions. Future research may define ways to influence this inflammatory cycle and hence to control or prevent exacerbations of these diseases.     

Malassezia Baillon, emerging clinical yeasts

The human and animal pathogenic yeast genus Malassezia has received considerable attention in recent years from dermatologists, other clinicians, veterinarians and mycologists. Some points highlighted in this review include recent advances in the technological developments related to detection, identification, and classification of Malassezia species. The clinical association of Malassezia species with a number of mammalian dermatological diseases including dandruff, seborrhoeic dermatitis, pityriasis versicolor, psoriasis, folliculitis and otitis is also discussed.     

House dust mite allergens induce interleukin 33 (IL-33) synthesis and release from keratinocytes via ATP-mediated extracellular signaling

In atopic diseases, the epithelium releases cytokines and chemokines that initiate skin inflammation. Atopic dermatitis (AD) is characterized by a disrupted epidermal barrier and is triggered or exacerbated by environmental stimuli such as house dust mite (HDM) allergens. The proinflammatory cytokine interleukin 33 (IL-33) plays an important role in the pathogenesis of AD, but how IL-33 production in keratinocytes is elicited by HDM is unknown. To that end, here we stimulated monolayer-cultured human keratinocytes and human living skin equivalents with Dermatophagoides pteronyssinus HDM extract to investigate its effects on IL-33 production from keratinocytes. The HDM extract induced intracellular expression of IL-33 and modulated its processing and maturation, triggering rapid IL-33 release from keratinocytes. Group 1 HDM allergen but not group 2 HDM allergen elicited IL-33 production. An ATP assay of keratinocyte culture supernatants revealed an acute and transient accumulation of extracellular ATP immediately after the HDM extract stimulation. Using the broad-spectrum P2 antagonist suramin, the specific purinergic receptor P2Y2 (P2RY2) antagonist AR-C118925XX, and P2RY2-specific siRNA, we discovered that the HDM extract-induced IL-33 expression was mainly dependent on extracellular ATP/P2Y2 signaling mediated by transactivation of epidermal growth factor receptor, followed by activation of the ERK kinase signaling pathway. Moreover, HDM extract–induced release of 25-kDa IL-33 from the keratinocytes depended on an extracellular ATP/P2 signaling–mediated intracellular Ca²⁺ increase. Our study demonstrates the new mechanism controlling the induction and maturation of keratinocyte-produced IL-33 by HDM allergens, an innate immune process that might play a role in AD development or severity.     

Functional expression and characterization of recombinant NADPH-P450 reductase from Malassezia globosa

Malassezia globosa is a common pathogenic fungus that causes skin diseases including dandruff and seborrheic dermatitis in humans. Analysis of its genome identified a gene (MGL_1677) coding for a putative NADPH-P450 reductase (NPR) to support the fungal cytochrome P450 enzymes. The heterologously expressed recombinant M. globosa NPR protein was purified, and its functional features were characterized. The purified protein generated a single band on SDS-PAGE at 80.74 kDa and had an absorption maximum at 452 nm, indicating its possible function as an oxidized flavin cofactor. It evidenced NADPH-dependent reducing activity for cytochrome c or nitroblue tetrazolium. Human P450 1A2 and 2A6 were able to successfully catalyze the O-deethylation of 7- ethoxyresorufin and the 7-hydroxylation of coumarin, respectively, with the support of the purified NPR. These results demonstrate that purified NPR is an orthologous reductase protein that supports cytochrome P450 enzymes in M. globosa.     

The importance of microscopic examination in the management of desquamative diseases of the scalp

After determining the usual malassezic biota of the scalp in adult, normal persons, 259 patients with different desquamative diseases were studied by a simple adhesive tape technique. The main purpose of this study was to investigate the utility of this technique to improve the diagnosis and treatment of patients. Most patients with seborrhoeic dermatitis and sebopsoriasis demonstrated large numbers of {it Malassezia} spp. cells corresponding to the so called ``pityrosporosis'. Only 43.6% of patients with pityriasis capitis (dandruff) presented with such a diagnosis. Symptomatic pityrosporosis of the scalp should be treated with imidazolic derivatives or other antifungal substances. Patients with psoriasis of the scalp showed a typical microscopic picture represented by parakeratosic (nucleated) keratinocytes with absence of lipophilic yeasts which should be attributed to the usual dryness of the scales .Microbial epidermitis (eczema) of the scalp revealed another characteristic picture constituted by abundant leukocytes and bacteria without the presence of yeasts. The different microscopic pictures seen with this simple technique for diseases of the scalp, offer an adjunct to make a proper diagnosis and to establish a convenient treatment in cases which are not clinically well defined. This revised version was published online in June 2006 with corrections to the Cover Date.     

Genotyping by RAPD-PCR analyses of Malassezia furfur strains from pityriasis versicolor and seborrhoeic dermatitis patients

Malassezia furfur is lypophilic yeast commonly associate with dermatological disorders. In the present work, we described the isolation of 47 M. furfur strains from three groups of patients: pityriasis versicolor (21 isolates), seborrhoeic dermatitis (15 isolates) and seborrhoeic dermatitis of the HIV positive patients (11 isolates). To investigate the identity of the strains at molecular level, DNA genomic of M. furfur strains were prepared and used to RAPD-PCR analyses. RAPD assay were carried out using two decamer primers and bands pattern generated were analyzed by an Unweighted Pair-Group Method (UPGMA). Dendrogram established a distinct differentiation between M. furfur isolates from pityriasis versicolor and seborrhoeic dermatitis patients with or without AIDS. We concluded that RAPD typing presented a high discriminatory power between strains studied in this work and can be applied in epidemiological investigation of skin disease causing by M. furfur.     

Pathological and clinical aspects of the diseases caused by Malassezia species

From veterinary point of view Malassezia pachydermatis has the greatest significance. It has been standing in the focus of interest since the early 1990s, mostly because of the frequency of otitis externa and dermatitis caused by this yeast in dogs. This is the only lipid-independent species in the genus Malassezia. It can be found in very large proportion on the skin of healthy animals, but can be isolated in much greater number from diseased dogs. It often causes illness together with other pathogens (e.g. Staphylococcus intermedius). Some breeds are predisposed. In addition to the treatment of the accidental concurrent diseases, therapy consists of systemic and/or topical antimicrobial treatment. Ketoconazole is used most frequently. Malassezia pachydermatis plays also a role in the skin disorders of other carnivores. It has little zoonotic potential, it can be dangerous to immunocompromised humans. The other Malassezia species have little veterinary importance, although M. sympodialis and M. globosa were isolated from asymptomatic animals (mostly cats) and from mixed infections.