A simple PCR-RFLP method for identification and differentiation of 11 Malassezia species

Fungal coexistence in the skin mycobiome: a study involving Malassezia, Candida, and Rhodotorula

Evidence of fungal coexistence in humans points towards fungal adaptation to the host environment, like the skin. The human commensal Malassezia has evolved, especially residing in sebum-rich areas of the mammalian body where it can get the necessary nutrition for its survival. This fungus is primarily responsible for skin diseases like Pityriasis versicolor (PV), characterized by hypo or hyperpigmented skin discoloration and erythematous macules. In this manuscript, we report a 19-year-old healthy female who presented with a one-year history of reddish, hypopigmented, asymptomatic lesions over the chest and a raised erythematous lesion over the face. Upon clinical observation, the patient displayed multiple erythematous macules and erythematous papules over the bilateral malar area of the face, along with multiple hypopigmented scaly macules present on the chest and back. Based on the above clinical findings, a diagnosis of PV and Acne vulgaris (AV) was made. Interestingly, the patient was immunocompetent and didn't have any comorbidities. Upon isolation of skin scrapings and post-culturing, we found the existence of three fungal genera in the same region of the patient's body. We further went on to confirm the identity of the particular species and found it to represent Malassezia, Rhodotorula, and Candida. We report how Malassezia, the predominant microbial resident skin fungus, coexists with other fungal members of the skin mycobiome. This study on an applied aspect of microbiology also shows how important it is to identify the fungal organism associated with skin infections so that appropriate therapeutics can be advised to avoid cases of relapse.

A Comprehensive Review of Identification Methods for Pathogenic Yeasts: Challenges and Approaches

Given the increasing incidence of yeast infections and the presence of drug-resistant isolates, accurate identification of the pathogenic yeasts is essential for the management of yeast infections. In this review, we tried to introduce the routine and novel techniques applied for yeast identification. Laboratory identification methods of pathogenic yeast are classified into three categories; I. conventional methods, including microscopical and culture-base methods II. biochemical/physiological-processes methods III. molecular methods. While conventional and biochemical methods require more precautions and are not specific in some cases, molecular diagnostic methods are the optimum tools for diagnosing pathogenic yeasts in a short time with high accuracy and specificity, and having various methods that cover different purposes, and affordable costs for researchers. Nucleotide sequencing is a reference or gold standard for identifying pathogenic yeasts. Since it is an expensive method, it is not widely used in developing countries. However, novel identification techniques are constantly updated, and we recommend further studies in this field. The results of this study will guide researchers in finding more accurate diagnostic method(s) for their studies in a short period of time.

Malassezia spp. and Candida spp. from patients with psoriasis exhibit reduced susceptibility to antifungals

INTRODUCTION

Psoriasis is a chronic inflammatory disease that affects over 125 million people worldwide. Many studies have shown the importance of the microbiome for psoriasis exacerbation.

AIM

Explore the fungal load and species composition of cultivable yeasts on the skin of psoriatic patients (PP) and healthy volunteers living in a tropical area and evaluate the susceptibility to antifungals.

METHODOLOGY

A cross-sectional study with 61 participants (35 patients and 26 healthy controls) was performed during August 2018 and May 2019. Clinical data were collected from patient interviewing and/or medical records review. Samples were collected by swabbing in up to five anatomic sites. Suggestive yeast colonies were counted and further identified by phenotypical tests, PCR-REA, and/or MALDI-TOF. Susceptibility of Malassezia spp. and Candida spp. to azoles, terbinafine, and amphotericin B was evaluated by broth microdilution.

RESULTS

Nearly 50% of the patients had moderate to severe psoriasis, and plaque-type psoriasis was the most common clinical form. Yeast colonies count was significantly more abundant among PP than healthy controls. Malassezia and Candida were the most abundant genus detected in all participants. Higher MIC values for ketoconazole and terbinafine were observed in Malassezia strains obtained from PP. Approximately 42% of Candida isolates from PP showed resistance to itraconazole in contrast to 12.5% of isolates from healthy controls. MIC values for fluconazole and amphotericin B were significantly different among Candida isolates from PP and healthy individuals.

CONCLUSION

This study showed that Malassezia and Candida strains from PP presented higher MIC values to widespread antifungal drugs than healthy individuals.

Genotypic Analysis of the Population Structure in Malassezia globosa and Malassezia restricta

The molecular characterization of Malassezia spp. isolates from animals and humans has not been thoroughly studied. Although a range of molecular methods has been developed for diagnosing Malassezia species, they have several drawbacks, such as inefficiency in differentiating all the species, high cost and questionable reproducibility. The present study aimed to develop VNTR markers for genotyping Malassezia isolated from clinical and animal samples. A total of 44 M. globosa and 24 M. restricta isolates were analyzed. Twelve VNTR markers were selected on seven different chromosomes (I, II, III, IV, V, VII and IX), six for each Malassezia species. The highest discriminatory power for a single locus was obtained with the STR-MG1 marker (0.829) and STR-MR2 marker (0.818) for M. globosa and M. restricta, respectively. After the analysis of multiple loci, 24 genotypes were noted among 44 isolates in M. globosa, with a discrimination index D of 0.943 and 15 genotypes were noted among 24 isolates in M. restricta, with a discrimination index D of 0.967. An endogenous infection was detected in two patients. Different genotypes of M. globosa strains colonized one patient. Interestingly, VNTR markers analysis revealed a carriage between a breeder and his dog in three cases for M. globosa and two for M. restricta. The FST (0.018 to 0.057) values indicate a low differentiation between the three populations of M. globosa. These results suggest a dominant clonal mode of reproduction in M. globosa. The typing of M. restricta showed a genotypic diversity of the strains, which can cause various skin pathologies. However, patient five was colonized with strains having the same genotype collected from different body parts (back, shoulder). VNTR analysis was capable of identifying species with high accuracy and reliability. More importantly, the method would facilitate monitoring Malassezia colonization in domestic animals and humans. It was shown that the patterns are stable and the method is discriminant, making it a powerful tool for epidemiological purposes.

Fungal Infections among Psoriatic Patients: Etiologic Agents, Comorbidities, and Vulnerable Population

Background

Psoriasis is a chronic inflammatory disorder of the skin and joint, affecting nearly 2-3% of the general population. It is assumed that imbalance between the types of natural microflora can accelerate the onset of the disease. Some fungi can play the role of superantigens and prolong chronic inflammation in the skin of psoriatic patients. The aim of the present investigation was to identify fungal species isolated from patients with psoriasis.

Methods

From March 2016 to May 2019, 289 patients with prior diagnosis of psoriasis were included in this survey. Direct microscopy with potassium hydroxide (KOH 10%), culture, urea hydrolysis, hair perforation test, and growth on rice grains were used to identify clinical isolates, phenotypically. For molecular identification of Candida species and Malassezia species, PCR-RFLP and PCR-sequencing were used, respectively.

Results

Forty-six out of 289 psoriatic patients had fungal infections (15.9%). Dermatophytes (54.3%), Candida spp. (19.5%), Malassezia spp. (15.2%), Aspergillus spp. (6.5%), and Fusarium spp. (4.3%) were the causative agents of fungal infections. Among Malassezia and Candida species, M. restricta (10.8%) and C. glabrata (8.7%) were the most prevalent species, respectively.

Conclusion

Our findings suggested that fungal pathogens, particularly dermatophytes, may play an important role in the pathogenicity of psoriasis. Also, due to the high rate of yeast colonization in the clinical samples of psoriatic patients, concomitant use of anti-inflammatory drugs and antifungals may represent an effective therapeutic approach for better management of chronic lesions among these patients. Mycological tests should be applied to indicate the incidence of fungal diseases in psoriatic patients.

Unveiling the structure of GPI-anchored protein of Malassezia globosa and its pathogenic role in pityriasis versicolor

Glycosylphosphatidylinositols (GPI)-anchored proteins (GpiPs) are related to the cell wall biogenesis, adhesion, interactions, protease activity, mating, etc. These proteins have been identified in many organisms, including fungi such as Neurospora crassa, Candida albicans, Saccharomyces cerevisiae, and Fusarium graminearum. MGL-3153 gene of Malassezia globosa (M. globosa) encodes a protein which is homologous of the M. restricta, M. sympodialis, M. Pachydermatis, and U. maydis GpiPs. Real-time PCR assay showed that the expression of MGL_3153 gene was significantly up-regulated among M. globosa isolated from patients with pityriasis versicolor (PV) compared to a healthy individual, suggesting the contribution of this gene in the virulence of M. globosa. Accordingly, the sequence of this protein was analyzed by bioinformatics tools to evaluate the structure of that. The conservation analysis of MGL-3153 protein showed that the C-terminal region of this protein, which is responsible for GPI-anchor ligation, was highly conserved during evolution while the N-terminal region just conserved in Malassezia species. Moreover, the predicted tertiary structure of this protein by homology modeling showed that this protein almost has alpha helix structure and represented a stable structure during 150 ns of molecular dynamic simulation. Our results revealed that this protein potentially belongs to GPI-anchored proteins and may contribute to the virulence of M. globosa which warrants further investigations in this area.

Identification of Malassezia species using direct PCR- sequencing on clinical samples from patients with pityriasis versicolor and seborrheic dermatitis

Background and Purpose :

Malassezia yeasts are lipophilic normal flora of the skin in humans and other warm-blooded vertebrates. This genus includes 18 species and is responsible for dermatological disorders, such as pityriasis versicolor, atopic dermatitis, seborrheic dermatitis, folliculitis, and dandruff. The aim of the present study was to identify the etiologic agents of Malassezia infections among the patients referring to the Referral Dermatology Clinic of Al-Zahra Hospital, Isfahan, Iran, during 2018-2019.

Materials and Methods:

For the purpose of the study, clinical specimens, including skin scrapings and dandruff, were collected and subjected to direct microscopy, culture, and polymerase chain reaction (PCR) sequencing. Direct PCR was performed on the clinical samples to amplify the D1/D2 region of 26S rDNA, using specific primers; subsequently, the amplicons were sent for sequencing.

Results:

This study was conducted on 120 patients with suspected pityriasis versicolor and seborrheic dermatitis, who referred to the Referral Dermatology Clinic of Al-Zahra Hospital, Isfahan, Iran, during 2018-2019. Out of this population, 50 (41.7%), 26 (52%), and 24 (48%) cases had Malassezia infection, pityriasis versicolor, and seborrheic dermatitis, respectively. Malassezia globosa was found to be the most prevalent species (n=29, 58%), followed by M. restricta (n=20, 40%), and M. arunalokei (n=1, 2%).

Conclusion:

The epidemiologic study was indicative of the frequency of some Malassezia species, such as M. globosa and M. restricta, in Isfahan, Iran. It can be concluded that direct PCR on clinical samples could be used as a simple, precise, effective, fast, and affordable method for research and even routine medical mycology laboratory studies.

Malassezia japonica is part of the cutaneous microbiome of free-ranging golden-headed lion tamarins (Leontopithecus chrysomelas - Kuhl, 1820)

We investigated Malassezia spp. in external ear canal and haircoat of free-ranging golden-headed lion tamarins (Leontopithecus chrysomelas). A total of 199 animals were restrained, and 597 clinical samples were collected. After the amplification of the 26S ribosomal gene by polymerase chain reaction (PCR), the RFLP technique was performed. Two additional PCR protocols were performed in 10 randomly selected strains. Malassezia sp. was isolated in 38.2% (76/199) of the animals and 14.6% (87/597) of the samples; all strains were lipodependent. The 10 sequenced strains showed a high identity with Malassezia japonica, species described in man, but not in animals, so far.

Antifungal activity of silver nanoparticles in combination with ketoconazole against Malassezia furfur

Malassezia furfur is lipophilic and lipid-dependent yeast, inhabitant of human skin microbiota associated with several dermal disorders. In recent years, along with the advances in nanotechnology and the incentive to find new antimicrobial drugs, there has been a growing interest in the utilization of nanoparticles for the treatment of skin microbial infections. This work aimed to study the in vitro inhibitory activity of silver nanoparticles (AgNP) against 41 M. furfur clinical isolates, visualize the interaction between AgNP-Malassezia, evaluate the synergism with ketoconazole (KTZ) and to produce an antimicrobial gel of AgNP–KTZ. The synthesized AgNP were randomly distributed around the yeast surface and showed a fungicidal action with low minimal inhibitory concentration values. AgNP showed no antagonistic effect with KTZ. The broad-spectrum antimicrobial property with fungicidal action of AgNP and its accumulation in affected areas with a sustained release profile, added to the great antifungal activity of KTZ against Malassezia infections and other superficial mycoses, allowed us to obtain a gel based on carbopol formulated with AgNP–KTZ with the potential to improve the topical therapy of superficial malasseziosis, reduce the number of applications and, also, prevent the recurrence.

Secreted Hydrolytic and Haemolytic Activities of Malassezia Clinical Strains

Malassezia yeasts are opportunistic pathogens associated with a number of skin diseases in animals and humans. The free fatty acids released through these organisms' lipase and phospholipase activities trigger inflammation in the host; thus, these lipase and phospholipase activities are widely recognised as some of the most important factors in Malassezia pathogenesis. In this study, we sought to investigate and examine the relationship between these secreted hydrolytic activities and haemolytic activity in newly isolated Malassezia clinical strains. This characterisation was expected to elucidate pathogenicity of this fungus. We isolated 35 clinical strains of Malassezia spp.; the most frequently isolated species were M. sympodialis and M. furfur. Next, we analysed the hydrolytic activities of all of these clinical isolates; all of these strains (except for one M. dermatis isolate) showed detectable lipase and phospholipase activities against 4-nitrophenyl palmitate and L-α-phosphatidylcholine, dipalmitoyl, respectively. Most of the M. globosa isolates showed higher lipase activities than isolates of other Malassezia species. In terms of phospholipase activity, no significant difference was observed among species of Malassezia, although one isolate of M. globosa showed considerably higher phospholipase activity than the others. All tested strains also exhibited haemolytic activity, both as determined using 5% (v/v) sheep blood agar (halo assay) and by quantitative assay. Although all tested strains showed detectable haemolytic activity, we did not observe an apparent correlation between the secreted lipase and phospholipase activities and haemolytic activity. We infer that the haemolytic activities of Malassezia spp. are mediated by non-enzymatic factor(s) that are present in the secreted samples.

MGL_3741 gene contributes to pathogenicity of Malassezia globosa in pityriasis versicolor

Dihydroxyacid dehydratase (DHAD) is a key enzyme in biosynthetic pathway of isoleucine and valine. This pathway is absent in human but exists in various organisms such as fungi. Using RNA-seq analysis in this study, we identified MGL_3741gene which encodes DHAD protein in Malassezia globosa (M. globosa). Furthermore, we found that mentioned gene is homologous to the Ustilago maydis, Saccharomyces cerevisiae, Aspergillus flavus, and Aspergillus fumigatus ILV3P. For understanding the probable role of this gene in pathogenicity of M. globosa, we applied Real-time PCR to investigate the differentially expressed of the MGL_3741 gene in healthy and pathogenic states. Our results indicate a significant difference between two mentioned stats. These results revealed that ILV3-like gene in M. globosa can be related to the pathogenicity of this yeast.

Diagnostics of Malassezia Species: A Review

Yeasts from the genus Malassezia belongs to normal commensal skin flora of warm-blooded vertebrates. These yeasts may act as opportunistic pathogens and cause skin diseases in humans and animals under certain conditions. The identification of Malassezia species is based on the phenotypic or genotypic diagnostics. The methods used for the phenotypic identification is determined by: the growth on Sabouraud agar, growth on selective media (Leeming-Notman agar, Dixon agar, Chrom Malassezia agar), the ability to utilise different concentrations of Tween, monitoring of the growth on CEL agar (soil enriched with castor oil) and TE agar (Tween-esculine agar), and the catalase test. The genotypic identification uses molecular methods like: the pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), amplified fragment lenght polymorphism (AFLP), denaturing gradient gel electrophoresis (DGGE), and the DNA sequence analysis.

Malassezia species in students from universities of Sabzevar, Northeastern Iran

BACKGROUND

Malassezia species, usually part of normal human skin microbiota, may also cause cutaneous infections, mainly pityriasis versicolor (PV) which may rapidly spread in crowded communities, particularly in students' dormitories and sport leisure centers.

OBJECTIVE

Few studies have been conducted on PV in students in the Middle East. The present study was designed to determine prevalence of Malassezia species and related diseases in students from city of Sabzevar, Northeast Iran.

METHODS

Specimens were collected from 189 students and analyzed by direct microscopy and cultures. Following PCR amplification of the large subunit of ribosomal DNA, species were identified by restriction fragment length polymorphism analysis (RFL-PCR).

RESULTS

PV was suspected for 28 students which was confirmed by direct examination and cultures. Cultures also revealed positive for 13 students with healthy skin. Four Malassezia species were identified, with M. restricta as the most prevalent. A higher rate of PV was observed compared to other regions in Iran. However, despite the lipophilic feature of Malassezia species, no significant association was observed between PV or Malassezia species and fatty skin or gender.

CONCLUSION

This study determined the frequencies of Malassezia species in part of Northeast Iran, but further studies are needed to identify risk factors for PV.

[In vitro antifungal activity of azoles and amphotericin B against Malassezia furfur by the CLSI M27-A3 microdilution and Etest® methods]

BACKGROUND

Malassezia furfur is a human skin commensal yeast that can cause skin and opportunistic systemic infections. Given its lipid dependant status, the reference methods established by the Clinical and Laboratory Standards Institute (CLSI) to evaluate antifungal susceptibility in yeasts are not applicable.

AIMS

To evaluate the in vitro susceptibility of M. furfur isolates from infections in humans to antifungals of clinical use.

METHODS

The susceptibility profile to amphotericin B, itraconazole, ketoconazole and voriconazole of 20 isolates of M. furfur, using the broth microdilution method (CLSI M27-A3) and Etest^®, was evaluated.

RESULTS

Itraconazole and voriconazole had the highest antifungal activity against the isolates tested. The essential agreement between the two methods for azoles antifungal activity was in the region of 60-85% and the categorical agreement was around 70-80%, while the essential and categorical agreement for amphotericin B was 10%.

CONCLUSIONS

The azoles were the compounds that showed the highest antifungal activity against M. furfur, as determined by the two techniques used; however more studies need to be performed to support that Etest^® is a reliable method before its implementation as a routine clinical laboratory test.

Is Malassezia nana the main species in horses' ear canal microbiome?

The objective of this study was to characterize genotypically Malassezia spp. isolated from the external ear canal of healthy horses. Fifty-five horses, 39 (70.9%) males and 16 (29.1%) females, from different breeds and adults were studied. External ear canals were cleaned and a sterile cotton swab was introduced to collect cerumen. A total of 110 samples were cultured into Dixon medium and were incubated at 32 °C for up to 15 days. Macro- and micromorphology and phenotypic identification were performed. DNA was extracted, strains were submitted to polymerase chain reaction technique, and the products obtained were submitted to Restriction Fragment Length Polymorphism using the restriction enzymes BstCI and HhaI. Strains were sent off to genetic sequencing of the regions 26S rDNA D1/D2 and ITS1-5.8S-ITS2 rDNA. Malassezia spp. were isolated from 33/55 (60%) animals and 52/110 (47%) ear canals. No growth on Sabouraud dextrose agar was observed, confirming the lipid dependence of all strains. Polymerase chain reaction-Restriction fragment length polymorphism permitted the molecular identification of Malassezia nana – 42/52 (81%) and Malassezia slooffiae – 10/52 (19%). Sequencing confirmed RFLP identification. It was surprising that M. nana represented over 80% of the strains and no Malassezia equina was isolated in this study, differing from what was expected.

Prevalence of oral Candida colonization in patients with diabetes mellitus

OBJECTIVES OF THE STUDY

We aimed to assess the prevalence of oral Candida colonization in patients with diabetes and its relationship with factors such as Candida species, serum glucose level, and the susceptibility rate of isolated yeasts to antifungals.

PATIENTS

Random samples were obtained from 113 patients with type 2 diabetes, 24 patients with type 1 diabetes, and 105 healthy controls.

MATERIALS AND METHODS

The samples were taken by swabbing the oral mucosa of patients with diabetes mellitus and healthy individuals. Afterwards the samples were inoculated onto CHROMagar-Candida. The growing colonies were counted, and the isolated yeasts were identified by PCR-RFLP and RapID methods. Various isolated species of Candida were also subjected to susceptibility testing of antibiotic drugs. Blood samples were taken to evaluate glycosylated hemoglobin (HbA1c).

RESULTS

Although the Candida carriage rate and density were statistically higher in diabetics than healthy individuals, no direct association was found between having high Candida-burden and glycosylated hemoglobin. The most commonly isolated species in both diabetics and controls was Candida albicans. Of the tested antifungal drugs, the highest rate of resistance was found against itraconazole, followed in frequency by ketoconazole and fluconazole.

CONCLUSIONS

This study identified a significant association between the poor glycemic control and the higher prevalence rates of Candida carriage and density in diabetic patients. In addition, a high prevalence of C. dubliniensis in diabetic patients was found, which might be misdiagnosed with its morphologically related species, C. albicans.

The spectrum of Malassezia species isolated from students with pityriasis vesicolor in Nigeria

Pityriasis versicolor (PV) is a common superficial fungal infection of the skin caused by Malassezia. Initially M. furfur was suggested as its main aetiological agent; however, more recent studies suggest M. globosa as the dominant species. The possibility of a variance in predominant species based on geographical basis has not been fully evaluated. The objective of this study was to identify the Malassezia species on affected and non-affected skin of students with PV who reside in a tropical environment (Abuja, Nigeria) and correlate them to clinical characteristics. In this study, the literature on prevalence of Malassezia genus in PV was also reviewed. Samples were taken from 304 PV lesions and 110 normal appearing skin. Microscopy, culture and identification of Malassezia species utilising polymerase chain reaction-restriction fragment length polymorphism analysis were performed. Three Malassezia species were detected in PV with the major species being M. furfur. On normal appearing skin, M. furfur (77.6%) and M. restricta (10.4%) were both detected. No case of M. globosa was identified in this study. There was no significant difference between species identified and clinical features of PV. M. furfur is probably still the most predominant species causing PV in the tropical environment.

Identification of Malassezia species in the facial lesions of Chinese seborrhoeic dermatitis patients based on DNA sequencing

The genus Malassezia is important in the aetiology of facial seborrhoeic dermatitis (FSD), which is the most common clinical type. The purpose of this study was to analyse the distribution of Malassezia species in the facial lesions of Chinese seborrhoeic dermatitis (SD) patients and healthy individuals. Sixty-four isolates of Malassezia were isolated from FSD patients and 60 isolates from healthy individuals. Sequence analysis of the internal transcribed spacer (ITS) region was used to identify the isolates. The most frequently identified Malassezia species associated with FSD was M. furfur (76.56%), followed by M. sympodialis (12.50%) and M. japonica (9.38%). The most frequently isolated species in healthy individuals were M. furfur (61.67%), followed by M. sympodialis (25.00%), M. japonica (6.67%), M. globosa (3.33%), and M. obtusa (3.33%). Overall, our study revealed that while M. furfur is the predominant Malassezia species in Chinese SD patients, there is no significant difference in the distribution of Malassezia species between Chinese SD patients and healthy individuals.

Molecular identification and prevalence of malassezia species in pityriasis versicolor patients from kashan, iran

Background:

Malassezia species are lipophilic yeasts found on the skin surface of humans and other warm-blooded vertebrates. It is associated with various human diseases, especially pityriasis versicolor, which is a chronic superficial skin disorder.

Objectives:

The aim of the present study was to identify Malassezia species isolated from patients’ samples affected by pityriasis versicolor, using molecular methods in Kashan, Iran.

Patients and Methods:

A total of 140 subjects, suspected of having pityriasis versicolor from Kashan, were clinically diagnosed and then confirmed by direct microscopic examination. The scraped skin specimens were inoculated in modified Dixon’s medium. DNA was extracted from the colonies and PCR amplification was carried out for the 26s rDNA region. PCR products were used to further restriction fragment length polymorphism by CfoI enzyme.

Results:

Direct examination was positive in 93.3% of suspected pityriasis versicolor lesions. No statistically significant difference was observed in the frequency of Malassezia species between women and men. The highest prevalence of tinea versicolor was seen in patients 21–30 years-of-age. No difference could be seen in the frequency of Malassezia species depending on the age of the patients. In total, 65% of patients with pityriasis versicolor had hyperhidrosis. The most commonly isolated Malassezia species in the pityriasis versicolor lesions were; Malassezia globosa (66%), M. furfur (26%), M. restricta (3%), M. sympodialis (3%), and M. slooffiae (2%). Malassezia species were mainly isolated from the neck and chest.

Conclusions:

This study showed M. globosa to be the most common Malassezia species isolated from Malassezia skin disorders in Kashan, Iran. The PCR-RFLP method was useful in the rapid identification of the Malassezia species. By using these methods, the detection and identification of individual Malassezia species from clinical samples was substantially easier.

Fungemia and interstitial lung compromise caused by Malassezia sympodialis in a pediatric patient

A case of fungemia with interstitial lung compromise caused by Malassezia sympodialis is reported in an obese pediatric patient on long-term treatment with inhaled corticosteroids for asthma. The patient was hospitalized due to a post-surgical complication of appendicitis. The patient was treated with amphotericin B for 3 weeks, with good clinical evolution and subsequent negative cultures.

Distribution of Malassezia species on the skin of patients with atopic dermatitis, psoriasis, and healthy volunteers assessed by conventional and molecular identification methods

Background

The Malassezia yeasts which belong to the physiological microflora of human skin have also been implicated in several dermatological disorders, including pityriasis versicolor (PV), atopic dermatitis (AD), and psoriasis (PS). The Malassezia genus has repeatedly been revised and it now accommodates 14 species, all but one being lipid-dependent species. The traditional, phenotype-based identification schemes of Malassezia species are fraught with interpretative ambiguities and inconsistencies, and are thus increasingly being supplemented or replaced by DNA typing methods. The aim of this study was to explore the species composition of Malassezia microflora on the skin of healthy volunteers and patients with AD and PS.

Methods

Species characterization was performed by conventional, culture-based methods and subsequently molecular techniques: PCR-RFLP and sequencing of the internal transcribed spacer (ITS) 1/2 regions and the D1/D2 domains of the 26S rRNA gene. The Chi-square test and Fisher’s exact test were used for statistical analysis.

Results

Malassezia sympodialis was the predominant species, having been cultured from 29 (82.9%) skin samples collected from 17 out of 18 subjects under the study. Whereas AD patients yielded exclusively M. sympodialis isolates, M. furfur isolates were observed only in PS patients. The isolation of M. sympodialis was statistically more frequent among AD patients and healthy volunteers than among PS patients (P < 0.03). Whether this mirrors any predilection of particular Malassezia species for certain clinical conditions needs to be further evaluated. The overall concordance between phenotypic and molecular methods was quite high (65%), with the discordant results being rather due to the presence of multiple species in a single culture (co-colonization) than true misidentification. All Malassezia isolates were susceptible to cyclopiroxolamine and azole drugs, with M. furfur isolates being somewhat more drug tolerant than other Malassezia species.

Conclusions

This study provides an important insight into the species composition of Malassezia microbiota in human skin. The predominance of M. sympodialis in both normal and pathologic skin, contrasts with other European countries, reporting M. globosa and M. restricta as the most frequently isolated Malassezia species.

Antifungal agent susceptibilities and interpretation of Malassezia pachydermatis and Candida parapsilosis isolated from dogs with and without seborrheic dermatitis skin

Malassezia pachydermatis and Candida parapsilosis are recognized as commensal yeasts on the skin of healthy dogs but also causative agents of eborrheic dermatitis, especially in atopic dogs. We determined and compared the susceptibility levels of yeasts isolated from dogs with and without seborrheic dermatitis (SD) using the disk diffusion method (DD) for itraconazole (ITZ), ketoconazole (KTZ), nystatin (NYS), terbinafine (TERB) and 5-fluorocytosine (5-FC) and the broth microdilution method (BMD) for ITZ and KTZ. The reliability between the methods was assessed using an agreement analysis and linear regression. Forty-five M. pachydermatis and 28 C. parapsilosis isolates were identified based on physiological characteristics and an approved molecular analysis. By DD, all tested M. pachydermatis isolates were susceptible to ITZ, KTZ, NYS and TERB but resistant to 5-FC. Only 46 - 60% of the tested C. parapsilosis isolates were susceptible to KTZ, TERB and 5-FC, but ITZ and NYS were effective against all. By BMD, over 95% of M. pachydermatis isolates were susceptible to KTZ and ITZ with an MIC90 < 0.03 and 0.12 μg/ml, respectively. The frequency of KTZ- and ITZ-resistant C. parapsilosis was 29% and 7%, and the MIC90 values were 1 μg/ml and 0.5-1 μg/ml, respectively. Regarding the agreement analysis, 2.2% of minor errors were observed in M. pachydermatis and 0.2-1% of very major errors occurred among C. parapsilosis. There were no significant differences in the yeast resistance rates between dogs with and without SD. KTZ and ITZ were still efficacious for M. pachydermatis but a high rate of KTZ resistant was reported in C. parapsilosis.

Plant and fungal diversity in gut microbiota as revealed by molecular and culture investigations

BACKGROUND

Few studies describing eukaryotic communities in the human gut microbiota have been published. The objective of this study was to investigate comprehensively the repertoire of plant and fungal species in the gut microbiota of an obese patient.

METHODOLOGY/PRINCIPAL FINDINGS

A stool specimen was collected from a 27-year-old Caucasian woman with a body mass index of 48.9 who was living in Marseille, France. Plant and fungal species were identified using a PCR-based method incorporating 25 primer pairs specific for each eukaryotic phylum and universal eukaryotic primers targeting 18S rRNA, internal transcribed spacer (ITS) and a chloroplast gene. The PCR products amplified using these primers were cloned and sequenced. Three different culture media were used to isolate fungi, and these cultured fungi were further identified by ITS sequencing. A total of 37 eukaryotic species were identified, including a Diatoms (Blastocystis sp.) species, 18 plant species from the Streptophyta phylum and 18 fungal species from the Ascomycota, Basidiomycota and Chytridiocomycota phyla. Cultures yielded 16 fungal species, while PCR-sequencing identified 7 fungal species. Of these 7 species of fungi, 5 were also identified by culture. Twenty-one eukaryotic species were discovered for the first time in human gut microbiota, including 8 fungi (Aspergillus flavipes, Beauveria bassiana, Isaria farinosa, Penicillium brevicompactum, Penicillium dipodomyicola, Penicillium camemberti, Climacocystis sp. and Malassezia restricta). Many fungal species apparently originated from food, as did 11 plant species. However, four plant species (Atractylodes japonica, Fibraurea tinctoria, Angelica anomala, Mitella nuda) are used as medicinal plants.

CONCLUSIONS/SIGNIFICANCE

Investigating the eukaryotic components of gut microbiota may help us to understand their role in human health.

Molecular biological identification of malassezia yeasts using pyrosequencing

Background

A Pyrosequencing assay has been used in identification of fungal species such as Candida or Aspergillus and diagnosis of pathogenic bacteria such as Helicobacter pylori but there has been no report on successful isolation and identification of Malassezia yeasts using the pyrosequencing method.

Objective

Examine the applicability and plausibility of the pyrosequencing method in identification of the Malassezia species.

Methods

At internal transcribed spacer (ITS) sites 1 and 2, three primers were developed using Pyrosequencing Assay Design Software (Biotage AB). Pyrosequencing was performed on 11 standard strains and 83 genomic DNA samples obtained from 66 healthy controls aged from 1 to 80.

Results

The eleven Malassezia standard species and 83 genomic DNA samples were successfully identified using the pyrosequencing assay.

Conclusion

The pyrosequencing method is a new tool for analysis of Malassezia yeasts, and its precision and rapidity suggests its clinical applicability.

A case report of tinea pedis caused by Trichosporon faecale in Iran

Trichosporon species are known as the causative agents of cutaneous infections and are involved in systemic, localized, as well as disseminated mycoses particularly in immunocompromised patients. Here we report a case of tinea pedis infection caused by Trichosporon faecale in a healthy 29-year-old woman in the north of Iran. Macroscopic and microscopic characteristics using direct examination as well as culture method revealed the causative agent as Trichosporon species. Molecular analysis of the internal transcribed spacer region validated the initial result and indicated that this case of tinea pedis was caused by T. faecale. The patient was recovered after treatment with topical myconazole accompanied with oral fluconazole.

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.

Distribution of malassezia species on the scalp in korean seborrheic dermatitis patients

BACKGROUND

Malassezia species play an important role in the pathogenesis of seborrheic dermatitis. In particular, M. restricta and M. globosa are considered to be the predominant organisms in seborrheic dermatitis of Western countries. However, species distribution of Malassezia in seborrheic dermatitis has not been clearly determined yet in Asia.

OBJECTIVE

To identify the distribution of Malassezia species on the scalp of seborrheic dermatitis patients in Korea using 26S rDNA PCR-RFLP analysis.

METHODS

A total of 40 seborrheic dermatitis patients and 100 normal healthy volunteers were included in this study. For the identification of Malassezia species, the scalp scales of the subjects were analyzed by 26S rDNA PCR-RFLP analysis.

RESULTS

The most commonly identified Malassezia species were M. restricta in the seborrheic dermatitis patients, and M. globosa in the normal controls. In the seborrheic dermatitis group, M. restricta was identified in 47.5%, M. globosa in 27.5%, M. furfur in 7.5%, and M. sympodialis in 2.5% of patients. In the healthy control group, M. globosa was identified in 32.0%, M. restricta in 25.0%, M. furfur in 8.0%, M. obtusa in 6.0%, M. slooffiae in 6.0%, and M. sympodialis in 4.0% of subjects.

CONCLUSION

M. restricta is considered to be the most important Malassezia species in Korean seborrheic dermatitis patients.

Advances in the identification of Malassezia

Members of the genus Malassezia are lypophilic and/or lipid-dependent, unipolar budding yeasts that can become pathogenic under the influence of particular predisposing factors (e.g., changes in the cutaneous microenvironment and/or alterations in host defences). This genus comprises at least 14 species, which have been identified traditionally based on their morphology and biochemical features. However, phenetic characteristics often do not allow the identification or delineation of closely related Malassezia spp., such that molecular tools need to be used to assist in fundamental studies of the epidemiology and ecology of Malassezia as well as aspects of the pathogenesis and disease caused by members of this genus. This article briefly reviews the morphological and biochemical methods commonly used for the identification of Malassezia as well as DNA technological methods that have been established for the specific identification of members of this genus and the diagnosis of their infections. New avenues for the development of improved molecular-diagnostic methods to overcome diagnostic limitations and to underpin fundamental investigations of this interesting group of yeasts are proposed.

Epidemiologic Study of Malassezia Yeasts in Seborrheic Dermatitis Patients by the Analysis of 26S rDNA PCR-RFLP

BACKGROUND

This case-control study concerns a molecular biological method based on the data gathered from a group of Korean subjects to examine the distribution of Malassezia yeasts in seborrheic dermatitis (SD) patients. Cultures for Malassezia yeasts were taken from the foreheads, cheeks and chests of 60 patients with SD and in 60 healthy controls of equivalent age.

OBJECTIVE

The purpose of this study is to identify the relationship between certain species of Malassezia and SD. This was done by analyzing the differences in the distribution of Malassezia species in terms of age and body parts of the host with healthy controls.

METHODS

26S rDNA PCR-RFLP, a fast and accurate molecular biological method, was used to overcome the limits of morphological and biochemical methods.

RESULTS

The positive Malassezia culture rate was 51.7% in patients with SD, which was lower than that of healthy adults (63.9%). M. restricta was dominant in patients with SD (19.5%). Likewise, M. restricta was identified as a common species (20.5%) in healthy controls. In the ages 31~40, M. restricta was found to be the most common species (31.6%) among SD patients.

CONCLUSION

According to the results of the study, the most frequently isolated species was M. restricta (19.5%) in patients with SD. There was no statistically significant difference in the distribution of Malassezia species between the SD patients and healthy control groups.

Molecular analysis of malassezia microflora on the skin of the patients with atopic dermatitis

BACKGROUND

The yeasts of the genus Malassezia are members of the normal flora on human skin and they are found in 75~80% of healthy adults. Since its association with various skin disorders have been known, there have been a growing number of reports that have implicated Malassezia yeast in atopic dermatitis (AD).

OBJECTIVE

The aim of the present study is to isolate the various Malassezia species from AD patients by using 26S rDNA (ribosomal Deoxyribonucleic acid) PCR-RFLP and to investigate the relationship between a positive Malassezia culture and the severity of AD.

METHODS

Cultures for Malassezia yeasts were taken from the scalp, cheek, chest, arm and thigh of 60 patients with atopic dermatitis. We used a rapid and accurate molecular biological method 26S rDNA PCR-RFLP, and this method can overcome the limits of the morphological and biochemical methods.

RESULTS

Positive Malassezia growth was noted on 51.7% of the patients with atopic dermatitis by 26S rDNA PCR-RFLP analysis. The overall dominant species was M. sympodialis (16.3%). M. restricta was the most common species on the scalp (30.0%) and cheek (16.7%). M. sympodialis (28.3%) was the most common species on the chest. The positive culture rate was the highest for the 11~20 age group (59.0%) and the scalp showed the highest rate at 66.7%. There was no significant relationship between the Malassezia species and SCORing for Atopic Dermatitis (SCORAD).

CONCLUSION

The fact that the cultured species was different for the atopic dermatitis lesion skin from that of the normal skin may be due to the disrupted skin barrier function and sensitization of the organism induced by scratching in the AD lesion-skin. But there was no relationship between the Malassezia type and the severity score. The severity score is thought to depend not on the type, but also on the quantity of the yeast.

Isolation and characterization of Malassezia spp. in healthy swine of different breeds

Malassezia spp. genus is represented by several lipophilic yeasts, normally present on the skin of many warm-blooded vertebrates, including man. Swine are one of the less investigated animal species. The aim of the present work was to study the occurrence of Malassezia spp. in the external ear canal of 408 healthy swine of different breeds, under different breeding conditions. For this purpose N. 185 free-ranging wild boars, N. 107 large size pigs and 116 Cinta Senese breed were selected. Animals were of both genders, with age ranging from 8 months to 4 years. The subjects were culturally and molecularly checked for Malassezia spp. Ninety-two out of 408 animals scored positive for Malassezia yeasts (22.5%). Malassezia pachydermatis, Malassezia sympodialis and Malassezia furfur were recognized. M. pachydermatis was the sole species isolated from wild boars (12.9%), Cinta Senese (20.7%) and juvenile large size pigs (13.6%); 88% of large size breeds adult subjects scored positive for M. sympodialis (63.6%) and M. furfur (22.7%), respectively. The study focus on scarcely investigated epidemiological aspects of Malassezia spp. in this animal species.

Comparison of Nested PCR and RFLP for Identification and Classification of Malassezia Yeasts from Healthy Human Skin

BACKGROUND

Malassezia yeasts are normal flora of the skin found in 75~98% of healthy subjects. The accurate identification of the Malassezia species is important for determining the pathogenesis of the Malassezia yeasts with regard to various skin diseases such as Malassezia folliculitis, seborrheic dermatitis, and atopic dermatitis.

OBJECTIVE

This research was conducted to determine a more accurate and rapid molecular test for the identification and classification of Malassezia yeasts.

METHODS

We compared the accuracy and efficacy of restriction fragment length polymorphism (RFLP) and the nested polymerase chain reaction (PCR) for the identification of Malassezia yeasts.

RESULTS

Although both methods demonstrated rapid and reliable results with regard to identification, the nested PCR method was faster. However, 7 different Malassezia species (1.2%) were identified by the nested PCR compared to the RFLP method.

CONCLUSION

Our results show that RFLP method was relatively more accurate and reliable for the detection of various Malassezia species compared to the nested PCR. But, in the aspect of simplicity and time saving, the latter method has its own advantages. In addition, the 26S rDNA, which was targeted in this study, contains highly conserved base sequences and enough sequence variation for inter-species identification of Malassezia yeasts.

Distribution of Malassezia species in patients with pityriasis versicolor in Northern Iran

PURPOSE

Malassezia yeasts are globally distributed agents of pityriasis versicolor and are implicated in the pathogenesis of seborrhoeic and atopic dermatitis. The aim of this study is to identify the Malassezia species obtained from pityriasis versicolor patients, using morphological, biochemical, physiological as well as Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) methods.

MATERIALS AND METHODS

The identification of Malassezia species is performed according to microscopic features and physiological characteristics, including catalase reaction and Tween assimilation tests. The DNA is extracted from cultured Malassezia using the glass bead, phenol-chloroform method. The internal transcribed spacer 1(ITS1) region is amplified and there is restricted digestion of the PCR products with two enzymes Cfo I and Bst F5I.

RESULTS

The most commonly isolated species is M. globosa (47.6%). RFLP analysis of the PCR products of the ITS1 region is in complete agreement with those from the DNA sequences of the internal transcribed spacer (ITS) 1 region and the biochemical tests.

CONCLUSION

Based on the findings of this study, it can be concluded that PCR-RFLP is a relatively simple and quick method, completely comparable to the routine methods used for Malassezia identification.

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.

The Investigation on the Distribution of Malassezia Yeasts on the Normal Korean Skin by 26S rDNA PCR-RFLP

BACKGROUND

Malassezia yeasts are normal flora of the skin that are discovered in 75~98% of health subjects, but since its association with various skin disorders have been known, many studies have been conducted in the distribution of the yeasts.

OBJECTIVE

To isolate, identify, and classify Malassezia yeasts from the normal human skin of Koreans by using the rapid and accurate molecular biology method (26S rDNA PCR-RFLP) which overcome the limits of morphological and biochemical methods, and to gather a basic database that will show its relation to various skin diseases.

METHODS

Malassezia yeasts were cultured from clinically healthy human skin using scrub-wash technique at five sites (forehead, cheek, chest, upper arm, and thigh) and swabbing technique at scalp in 160 participants comprised of 80 males and 80 females aged from 0 to 80. Identification of obtained strains were placed into the one of the 11 species by 26S rDNA PCR-RFLP.

RESULTS

An overall positive culture rate was 62.4% (599/960). As shown in the experiment groups by their age, the positive culture rate was the highest (74.2%) in the age 21~30 and 31~40 (89/120). In the experiment groups by different body areas, the scalp showed the highest positive culture rate of 90% (144/160). On analysis of 26S rDNA PCR-RFLP, M. globosa was the most predominant species in the age 0~10 (32.8%), 11~20 (28.9%), 21~30 (32.3%). M. restricta was identified as predominant species in the age 41~50 (27.9%), 61~70 (31.5%) and 71~80 (24.0%). In the age 31~40 years, M. sympodialis was found to be the most common species (24.6%). According to body site, M. restricta was more frequently recovered in the scalp (56.8%), forehead (39.8%) and cheek (24.0%) and while M. globosa was more frequently recovered in the chest (36.8%). Higher positive culture rates of Malassezia yeasts were shown in male subjects than female counterparts in all body areas except scalp (p<0.05). Especially in this study, M. dermatis, newly isolated Malassezia species from atopic dermatitis patient in Japan, was isolated and identified in 19 cases (1.9%) in healthy subjects.

CONCLUSION

The key is to recognize the existence of a difference in the type of Malassezia species in different ages as well as body areas, which reflects differing skin lipid levels in various ages and different body areas. Moreover, 26S rDNA PCR-RFLP analysis which was opted in this study could provide a sensitive and rapid identification system for Malassezia species, which may be applied to epidemiological surveys and clinical practice.

Physiological and molecular characterization of atypical isolates of Malassezia furfur

The species constituting the genus Malassezia are considered to be emergent opportunistic yeasts of great importance. Characterized as lipophilic yeasts, they are found in normal human skin flora and sometimes are associated with different dermatological pathologies. We have isolated seven Malassezia species strains that have a different Tween assimilation pattern from the one typically used to differentiate M. furfur, M. sympodialis, and M. slooffiae from other Malassezia species. In order to characterize these isolates of Malassezia spp., we studied their physiological features and conducted morphological and molecular characterization by PCR-restriction fragment length polymorphism and sequencing of the 26S and 5.8S ribosomal DNA-internal transcribed spacer 2 regions in three strains from healthy individuals, four clinical strains, and eight reference strains. The sequence analysis of the ribosomal region was based on the Blastn algorithm and revealed that the sequences of our isolates were homologous to M. furfur sequences. To support these findings, we carried out phylogenetic analyses to establish the relationship of the isolates to M. furfur and other reported species. All of our results confirm that all seven strains are M. furfur; the atypical assimilation of Tween 80 was found to be a new physiological pattern characteristic of some strains isolated in Colombia.