Identification of Malassezia yeast species isolated from patients with pityriasis versicolor

Pityriasis versicolor (PV) is a disease with worldwide distribution. Twelve different species of Malassezia yeast have been described. The objective of this study was to determine which species of Malassezia are more prevalent in patients with pityriasis versicolor. Samples were collected by scraping the lesions of 87 patients with a clinical suspicion of pityriasis versicolor. The samples were then submitted to fungal microscopy and culture to identify the species. The species found were: Malassezia sympodialis (30%), Malassezia furfur (25.7%), Malassezia globosa (22.7%), Malassezia restricta (12.1%), Malassezia obtusa (7.6%) and Malassezia slooffiae (1.5%).     

Distribution of Malassezia species in patients with psoriasis and healthy individuals in Tehran, Iran

Background: Psoriasis is a non‐contagious disorder that affects the skin as red scaly patches. Although the role of Malassezia species in the pathogenesis of psoriasis is still not fully understood, it is thought that these lipophilic yeasts might be a trigger factor in the exacerbation of psoriatic lesions. Methods: Using culture in a specific medium followed by the polymerase chain reaction‐restriction fragment length polymorphism method, the presence of Malassezia species in the skin of 110 patients with psoriasis was compared with that in a control group of 123 healthy patients. Results: The recovery rate of Malassezia species from the skin of patients with psoriasis was significantly lower than that in the controls. In both psoriatic and healthy skin, Malassezia globosa was isolated as the predominant species. In psoriatic patients, the rate of colonization of Malassezia furfur and Malassezia restricta was almost twice that in the controls, whereas M. globosa was isolated more frequently from healthy individuals than from patients. Conclusions: Considering the higher lipase activity secretion by M. furfur in comparison with other Malassezia species, the enzymatic release of arachidonic acid and its metabolites by M. furfur may exacerbate the inflammatory and hyperproliferative changes observed in psoriasis.     

Malassezia species in healthy skin and in dermatological conditions

The genus Malassezia comprises lipophilic species, the natural habitat of which is the skin of humans and other warm‐blooded animals. However, these species have been associated with a diversity of dermatological disorders and even systemic infections. Pityriasis versicolor is the only cutaneous disease etiologically connected to Malassezia yeasts. In the other dermatoses, such as Malassezia folliculitis, seborrheic dermatitis, atopic dermatitis, and psoriasis, these yeasts have been suggested to play pathogenic roles either as direct agents of infection or as trigger factors because there is no evidence that the organisms invade the skin. Malassezia yeasts have been classified into at least 14 species, of which eight have been isolated from human skin, including Malassezia furfur, Malassezia pachydermatis, Malassezia sympodialis, Malassezia slooffiae, Malassezia globosa, Malassezia obtusa, Malassezia restricta, Malassezia dermatis, Malassezia japonica, and Malassezia yamatoensis. Distributions of Malassezia species in the healthy body and in skin diseases have been investigated using culture‐based and molecular techniques, and variable results have been reported from different geographical regions. This article reviews and discusses the latest available data on the pathogenicity of Malassezia spp., their distributions in dermatological conditions and in healthy skin, discrepancies in the two methods of identification, and the susceptibility of Malassezia spp. to antifungals.     

Molecular analysis of Malassezia species isolated from Israeli patients with pityriasis versicolor

Background Pityriasis versicolor (PV) is a common superficial fungal infection of the skin caused by Malassezia species. The clinical significance of each of these species is not fully understood. M. furfur has long been identified as the causative agent of PV. Several recent studies suggest that M. globosa is most frequently associated with PV. Objectives The aim of this study was to examine the prevalence of Malassezia species in affected and unaffected skin in Israeli patients with PV using a polymerase chain reaction (PCR)‐based culture‐independent method. Methods Samples were taken from affected skin of 75 patients with PV (35 females and 40 males, age range 18–65 years) who visited our outpatient clinic and from unaffected skin in 26 patients for direct microscopy and detection of Malassezia species using a PCR‐based method. Results The major Malassezia species in PV was M. globosa, found in 97.3% (73 of 75) of samples from affected skin and 80.8% (21 of 26) samples of unaffected skin. M. restricta was associated with M. globosa in 1.3% (one of 75) of patients. No cases of M. furfur were detected in this study. There was no difference in the distribution of Malassezia species between affected and unaffected skin. Conclusion Based on the PCR test, we have shown that M. globosa is probably most frequently associated with PV.     

Interleukin-8 immunoreactivity in the skin of healthy subjects and patients with palmoplantar pustulosis and psoriasis.

Previous studies have shown that neutrophil-activating peptide 1/interleukin-8 (IL-8) is present in psoriatic scales and to a lesser extent in normal human epidermis. A panel of monoclonal antibodies and polyclonal antisera raised against IL-8 was used to localize IL-8 with immunoperoxidase techniques in non-lesional and lesional skin of patients with psoriasis and palmo-plantar pustulosis (PPP), and in corresponding sites from healthy subjects. Intracellular IL-8 immunoreactivity was found in all epidermal cell layers in biopsies of healthy subjects and in non-lesional and lesional skin in both PPP and psoriasis. The most intense immunolabeling was regularly found in the basal cell layer. Intercellular epidermal IL-8 immunolabeling was regularly detected in lesional biopsies in PPP and psoriasis, but not in healthy subjects or non-lesional skin in PPP and psoriasis. No intercellular immunolabeling was detected after successful treatment of lesional skin. The majority of cells along the eccrine sweat glands, dermal mononuclear cell infiltrates, and endothelial cells were IL-8 immunoreactive in all biopsies studied. The present study suggests that IL-8, its precursor form, or, alternatively, a degradation product is present in normal human epidermis.     

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。     

Molecular analysis of Malassezia microflora in the lesional skin of psoriasis patients

Systemic and focal infections by microorganisms have been known to induce or exacerbate psoriasis. To investigate the role of Malassezia species in the development of psoriasis, we analyzed the Malassezia microflora in psoriasis patients using a nested polymerase chain reaction (PCR) assay, and compared it with those in atopic dermatitis (AD) patients and healthy subjects. Fungal DNA was directly collected from the lesional and non-lesional skin of the trunk of 22 psoriasis patients by applying a transparent dressing. The extracted DNA was amplified by using specific primers designed for the PCR in the intergenic spacer or internal transcribed spacer area of the ribosomal RNA. All nine of the Malassezia species were detected at different rates from the 22 psoriasis patients. The overall detection rates in lesional and non-lesional skin of M. restricta, M. globosa and M. sympodialis were high (96%, 82% and 64%, respectively), whereas the detection rates of the other species were relatively low. However, there was no difference in the rates between lesional and non-lesional skin areas. The average number of Malassezia species detected in overall sites of the psoriasis patients was 3.7 +/- 1.6 species, although this fact showed no correlation with the severity of the symptoms. The number of Malassezia species detected was 4.1 +/- 1.9 in the AD patients, and 2.8 +/- 0.8 in the healthy subjects, suggesting that the skin microflora of psoriasis patients and AD patients show greater diversity than that of healthy subjects.     

Molecular analysis of Malassezia species isolated from hospitalized neonates

Abstract:  Malassezia species are a part of the skin microflora of neonates. Under certain circumstances, they can cause diseases ranging from simple pustulosis to lifethreatening fungemia in newborn infants. Little information is available about the epidemiology of Malassezia species in neonates. In the present study, we successfully isolated Malassezia yeasts from 68.7% of hospitalized neonates. Using the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFPL), M. furfur (88.06%) was identified as the most isolated species, followed in frequency by M. globosa (10.48%), M. obtusa (0.73%), and M. slooffiae (0.73%). Among the variables studied, only a longer stay in the ward resulted in a higher colonization rate. Using multiple logistic regression, only the type of hospital and ward had some effects on the colonization rate. Our results supported the hypothesis that neonates acquire Malassezia flora through direct contact with their mothers or hospital personnel.     

Malassezia folliculitis on the scalp of a 12-year-old healthy child

Malassezia folliculitis is a condition chracterized by itchy follicular papules and pustules with erythema. Malassezia yeasts are the pathogens in this condition. It is mainly located on the back, shoulders, and chest. Presented here is a 12-year-old boy with malassezia folliculitis on the scalp. The case was found to be worthy of presentation because it rarely occurs in childhood and is rarely located on the scalp.     

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.     

Comparative study of staphylococci from the skin of atopic dermatitis patients and from healthy subjects

BACKGROUND: Bacterial infections occur frequently on the skin of atopic dermatitis (AD) patients. The objectives of this study were to evaluate the microbiology of the skin of AD patients for staphylococci, the frequency and density of each species, and their susceptibility to antimicrobial drugs. METHODS: To study the staphylococci present on the skin of 21 AD outpatients and of 12 healthy subjects (HS), cutaneous organisms were obtained using the contact-plate method. RESULTS: Staphylococcus aureus was isolated in 85.7% of AD patients (mild type, 77.8%; moderate type, 87.8%; and severe type, 100%) and in 25% of HS, while Staphylococcus epidermidis was isolated in 83.3% of HS and in 38.1% of AD patients. Among the coagulase-negative staphylococci (CNS) identified, S. epidermidis was the common type and several other CNS were detected in both AD patients and HS. As the eruption grade of dermatitic skin became more severe, the average density of S. aureus increased (severe, 2.68 +/- 0.86; moderate, 2.49 +/- 0.48; mild, 2.28 +/- 0.44). A reversed tendency was seen in S. epidermidis (severe, 1.80; moderate, 1.90; mild, 2.10). Among nine antimicrobial drugs tested against S. aureus, S. epidermidis, and some other types of CNS isolates, vancomycin (VCM) and minocycline (MINO) were the most active, gentamycin (GM) was the less active, and ampicillin (ABPC) was the least active. CONCLUSIONS: The skin of AD patients was more frequently colonized with S. aureus than that of normal controls. As the severity of the AD lesions increased, the numbers of S. aureus isolated increased. The skin of HS was more colonized with S. epidermidis. Other species of CNS were isolated from several cases of AD patients and HS. In addition, S. aureus, S. epidermidis, and the other CNS showed poor susceptibility to some of the tested antimicrobial drugs.     

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

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

Expression of HLA-DR antigen in skin from patients with psoriasis

Using murine monoclonal antibodies against human HLA-DR antigen and against human T cells, we investigated the indirect immunofluorescence staining pattern of involved and uninvolved skin from patients with psoriasis. The staining pattern of involved psoriatic epidermis is different from the pattern seen in uninvolved skin from the same patient and consists of scattered, single HLA-DR positive cells alternating with groups of HLA-DR positive cells. These HLA-DR positive cell clusters can be seen at any level of the epidermis. In some patients, the dermis of involved skin shows prominent accumulations of T cells which are HLA-DR positive and thus represent activated T cells.     

从包皮龟头炎患者皮损处分离鉴定马拉色菌

目的：了解马拉色菌属各菌种在包皮龟头炎皮损处的构成及其在发病中的作用。方法：从患处取材直接镜检查见马拉色菌孢子和(或)菌丝的包皮龟头炎患者作为研究对象。用胶带法取材后分别接种在含菜子油的培养基及无放线菌酮的沙堡培养基分离菌种。依据生理生化和形念学特点及转种到科玛嘉显色培养基和米粉吐温80琼脂培养结果鉴定出马拉色菌和(或)念珠菌。结果：81例患者中有57例(70．37％)培养并鉴定出马拉色菌(共60株)，其中糠秕马拉色菌20株(33．33％），合轴马拉色菌18株(30．00％)，钝形马拉色菌17株(28．33％)，球形马拉色菌5株(8．33％)。有37例同时分离到念珠菌(其中72．97％为白念珠菌）。44例仅检出马拉色菌的患者中有23例接受抗真菌治疗。结论：糠秕马拉色菌、合轴马拉色菌、钝形马拉色菌是包皮龟头炎患者皮损处的主要菌种；马拉色菌可能单独或与念珠菌协同引起包皮龟头炎。     

Phospholipase activity after β‐endorphin exposure discriminates Malassezia strains isolated from healthy and seborrhoeic dermatitis skin

Background Phospholipase activity and its induction by β‐endorphin have been associated with pathogenic Malassezia pachydermatis animal isolates. Objective To evaluate Malassezia phosholipase activity in human isolates from seborrhoeic dermatitis (SD) and healthy controls before and after β‐endorphin exposure. Methods Eighty‐four volunteers with or without SD (N = 41) were sampled. Isolated Malassezia strains were incubated in Dixon’s medium with and without 100 nmol/L β‐endorphin. Subsequently, phospholipase activity was assessed in egg‐yolk agar and the results were compared employing Wilcoxon sign test for paired data, chi‐squared test and multinomial logistic regression analysis. Results A total of 64 Malassezia strains were isolated. SD strains tended to have decreased phospholipase activity before (P = 0.057) and increased after exposure to β‐endorphin (P = 0.061) compared to isolates from healthy skin. Phospholipase activity after β‐endorphin exposure related to basal enzyme activity as a measure of per strain phospholipase inducibility by β‐endorphin did not depend on Malassezia species (P = 0.652). However, this latter biochemical trait discriminates strains isolated from SD lesional and healthy skin (P = 0.036). Conclusion β‐endorphin exposure modifies the in vitro phosholipase activity in Malassezia species isolated from SD lesional skin. This is in accordance with emerging evidence that enhanced local lipase activity is involved in the pathogenesis of SD.     

Scalp psoriasis: synergy between the Malassezia yeasts and skin irritation due to calcipotriol

To investigate if there is a synergy between the presence of the Malassezia yeasts and the adverse reaction during treatment of scalp psoriasis with calcipotriol scalp solution, patients were treated with itraconazole to reduce the number of Malassezia yeasts. This study was a double-blind, placebo-controlled parallel group study between oral itraconazole or placebo for 8 weeks in patients with scalp psoriasis. After 2 weeks, calcipotriol scalp solution was applied twice daily for 6 weeks. Altogether 137 patients, 67 in the itraconazole group and 70 in the placebo group, comprised the intention-to-treat population. There were 13 (19.4%) patients with local skin irritation in the itraconazole group compared to 33 (47.1%) in the placebo group (p < 0.001). The skin irritation was significantly lower in patients with a low number of cultured Malassezia yeasts (p = 0.017). Thus, when Malasessia was eliminated or the numbers reduced, the irritation produced by calcipotriol was significantly diminished.