Malassezia vespertilionis sp. nov.: a new cold-tolerant species of yeast isolated from bats

Extracellular phospholipase production by Malassezia pachydermatis strains and its inhibition by selected antimycotics and plant essential oil components

Extracellular phospholipase (EPL) plays an important role in the pathogenesis of the yeast Malassezia pachydermatis. Currently, the attention of researchers is focused on studying the virulence factors involved in this process and searching solutions to reduce their activity. One of the options is the use of natural remedies as anti-virulence agents. This study is aimed at investigating the production of extracellular phospholipase in M. pachydermatis strains (18 samples) and followed by the time-dependent inhibitory effect of selected azole antifungals (itraconazole, posaconazole and voriconazole) and plant essential oil components (terpinen-4-ol, thymol, carvacrol, eugenol and geraniol), evaluated by Egg Yolk Agar plate method. Almost all strains (17 isolates, (94.4%) were found to be intense EPL producers. A significant, time-dependent inhibition of EPL was noted after 1-, 3- and 6-h exposure of Malassezia cells to itraconazole (26.4%, 47.2% and 50.9%, respectively) compared to exposure to posaconazole (26.4%, 28.3% and 28.3%, respectively) and voriconazole (18.8%, 20.8% and 35.8%, respectively). After one-hour exposure to plant essential oil components, the best inhibitory effect was recorded for eugenol (62.3%), followed by terpinen-4-ol and thymol (56.6%), geraniol (41.5%) and carvacrol (26.4%). A 3-h exposure revealed that thymol retained the best inhibitory effect (88.7%) on EPL production, followed by carvacrol (73.6%), eugenol (56.6%), terpinen-4-ol (52.8%) and geraniol (49.1%). After 6-h exposure, no growth of M. pachydermatis strains exposed to carvacrol was observed, and the inhibitory efficiency for the other tested essential oil (EO) components achieved 88.7%. The obtained results indicate the promising efficacy of plant essential oils components in the inhibition of virulence factors such as EPL production.

Coexistence of Malassezia Species and Microsporum canis in the Lesions of Adult with Tinea Capitis

Tinea capitis, primarily caused by dermatophytes such as Trichophyton and Microsporum species, is a superficial fungal infection affecting the scalp and hair, commonly observed in prepubertal children but rare in adults. Here we report a unique case of an adult female with tinea capitis presenting as diffused alopecia and erythema inflammation on the scalp's apex, mimicking seborrheic dermatitis. Examination of the hair and scalp using fluorescence microscopy and fungal culture identified the presence of hyphae from Malassezia globosa, Malassezia furfur and Microsporum canis. The patient underwent with oral antifungal treatment for 3 months, resulting in the resolution of the rash and subsequent hair regrowth, with no recurrence during 6-month follow-up. In vitro co-culture experiments of Microsporum canis and Malassezia (both Malassezia globose and Malassezia furfur) revealed that Malassezia appears to facilitate Microsporum canis growth, while the reverse was not observed. This data suggests that Malassezia's use of long-chain fatty acids by might reduce its antibacterial effect, potentially aiding adult tinea capitis development caused by Microsporum canis.

Anti-Malassezia globosa (MYA-4889, ATCC) activity of Thai propolis from the stingless bee Geniotrigona thoracica

Malassezia globosa, a lipophilic pathogen, is known to be involved in various chronic skin diseases. Unfortunately, the available treatments have unwanted side effects and microbial drug resistance is evolving. As the antimicrobial activity of propolis is outstanding, this study aimed to examine the potential of propolis from the stingless bee Geniotrigona thoracica against the yeast. Anti-M. globosa growth activity was ascertained in agar well diffusion and broth microdilution assays and the inhibitory concentration value at 50 % (IC50) was determined. Since the yeast cannot synthesize its own fatty acids, extracellular lipase is important for its survival. Here, anti-M. globosa extracellular lipase activity was additionally investigated by colorimetric and agar-based methods. Compared to the crude hexane and crude dichloromethane extracts, the crude methanol partitioned extract (CMPE) exhibited the best anti-M. globosa growth activity with an IC50 of 1.22 mg/mL. After CMPE was further enriched by silica gel column chromatography, fraction CMPE1 (IC50 of 0.98 mM or 184.93 μg/mL) presented the highest activity and was later identified as methyl gallate (MG) by nuclear magnetic resonance analysis. Subsequently, MG was successfully synthesized and shown to have a similar activity, and a minimal fungicidal concentration of 43.44 mM or 8.00 mg/mL. However, lipase assay analysis suggested that extracellular lipase might not be the main target mechanism of MG. This is the first report of MG as a new anti-Malassezia compound. It could be a good candidate for further developing alternative therapeutic agents.

Malassezia dermatitis in dogs and cats

Malassezia are members of the mycobiome of dogs and cats. In the presence of an underlying disease, these yeasts can proliferate, attach to the skin or mucosa to induce a secondary Malassezia dermatitis, otitis externa or paronychia. Since allergic dermatitis is one of the most common underlying causes, diagnostic investigation for allergy is often indicated. Cats may suffer from various other underlying problems, especially where Malassezia dermatitis is generalised. Malassezia dermatitis in dogs and cats is chronic, relapsing and pruritic. Direct cytology from dermatological lesions and the ear canal, showing "peanut-shaped" budding yeasts, facilitates a rapid and reliable diagnosis. Topical treatment includes antiseptic and antifungal azole-based products. Systemic treatment with oral antifungals is indicated only in severe or refractory disease. Identification and treatment of the underlying cause is essential for an optimal response. In this evidence-based narrative review, we discuss the clinical presentation of Malassezia dermatitis in dogs and cats, underlying comorbidities, and diagnostic considerations. Treatment is discussed in light of emerging evidence of antifungal resistance and the authors' clinical experience.

A minimally invasive, field-applicable CRISPR/Cas biosensor to aid in the detection of Pseudogymnoascus destructans, the causative fungal agent of white-nose syndrome in bats

The accessibility to CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein) genetic tools has given rise to applications beyond site-directed genome editing for the detection of DNA and RNA. These tools include precise diagnostic detection of human disease pathogens, such as SARS-CoV-2 and Zika virus. Despite the technology being rapid and cost-effective, the use of CRISPR/Cas tools in the surveillance of the causative agents of wildlife diseases has not been prominent. This study presents the development of a minimally invasive, field-applicable and user-friendly CRISPR/Cas-based biosensor for the detection of Pseudogymnoascus destructans (Pd), the causative fungal agent of white-nose syndrome (WNS), an infectious disease that has killed more than five million bats in North America since its discovery in 2006. The biosensor assay combines a recombinase polymerase amplification (RPA) step followed by CRISPR/Cas12a nuclease cleavage to detect Pd DNA from bat dermal swab and guano samples. The biosensor had similar detection results when compared to quantitative PCR in distinguishing Pd-positive versus negative field samples. Although bat dermal swabs could be analysed with the biosensor without nucleic acid extraction, DNA extraction was needed when screening guano samples to overcome inhibitors. This assay can be applied to help with more rapid delineation of Pd-positive sites in the field to inform management decisions. With further optimization, this technology has broad translation potential to wildlife disease-associated pathogen detection and monitoring applications.

A review of sebum in mammals in relation to skin diseases, skin function, and the skin microbiome

Diseases vary among and within species but the causes of this variation can be unclear. Immune responses are an important driver of disease variation, but mechanisms on how the body resists pathogen establishment before activation of immune responses are understudied. Skin surfaces of mammals are the first line of defense against abiotic stressors and pathogens, and skin attributes such as pH, microbiomes, and lipids influence disease outcomes. Sebaceous glands produce sebum composed of multiple types of lipids with species-specific compositions. Sebum affects skin barrier function by contributing to minimizing water loss, supporting thermoregulation, protecting against pathogens, and preventing UV-induced damage. Sebum also affects skin microbiome composition both via its antimicrobial properties, and by providing potential nutrient sources. Intra- and interspecific variation in sebum composition influences skin disease outcomes in humans and domestic mammal species but is not well-characterized in wildlife. We synthesized knowledge on sebum function in mammals in relation to skin diseases and the skin microbiome. We found that sebum composition was described for only 29 live, wild mammalian species. Sebum is important in dermatophilosis, various forms of dermatitis, demodicosis, and potentially white-nose syndrome. Sebum composition likely affects disease susceptibility, as lipid components can have antimicrobial functions against specific pathogens. It is unclear why sebum composition is species-specific, but both phylogeny and environmental effects may drive differences. Our review illustrates the role of mammal sebum function and influence on skin microbes in the context of skin diseases, providing a baseline for future studies to elucidate mechanisms of disease resistance beyond immune responses.

In vitro sensitivity of Malassezia furfur isolates from HIV-positive and negative patients to antifungal agents

INTRODUCTION

Malassezia is a lipophilic and lipid-dependent yeast genus belonging to the skin microbiota of humans and other animals. However, due to dysbiosis processes or other factors in the host, this yeast can cause different pathologies, ranging from skin diseases, such as seborrheic dermatitis, to fungemia. Isolation of Malassezia furfur has been reported in HIV-positive patients with or without skin lesions. Due to its opportunistic nature and its variable resistance to antifungal compounds, it is relevant to know the Malassezia sensitivity profiles.

OBJECTIVE

To determine the sensitivity to different antifungal agents, of clinical isolates of M. furfur obtained from HIV-positive or negative patients, with or without seborrheic dermatitis.

MATERIALS AND METHODS

Assessment of isolates sensitivity to itraconazole, voriconazole, fluconazole, and amphotericin B was performed by two techniques: (1) Broth microdilution using Clinical and Laboratory Standards Institute (CLSI) protocol M27-A3 with modifications; and (2) agar tests using Etest®.

RESULTS

Isolates obtained from HIV patients showed an increase in the minimum inhibitory concentration of fluconazole, voriconazole, and amphotericin B, compared with those of non-HIV patients. Itraconazole was the antifungal with the lowest minimum inhibitory concentration (MIC) in most isolates.

CONCLUSION

We observed differences in the sensitivity profiles of M. furfur isolates according to the context of the patient. High MIC of antifungals like fluconazole, commonly used for treating pathologies caused by Malassezia, were identified.

Frequent transitions in mating-type locus chromosomal organization in Malassezia and early steps in sexual reproduction

Fungi in the basidiomycete genus Malassezia are the most prevalent eukaryotic microbes resident on the skin of human and other warm-blooded animals and have been implicated in skin diseases and systemic disorders. Analysis of Malassezia genomes revealed that key adaptations to the skin microenvironment have a direct genomic basis, and the identification of mating/meiotic genes suggests a capacity to reproduce sexually, even though no sexual cycle has yet been observed. In contrast to other bipolar or tetrapolar basidiomycetes that have either two linked mating-type-determining (MAT) loci or two MAT loci on separate chromosomes, in Malassezia species studied thus far the two MAT loci are arranged in a pseudobipolar configuration (linked on the same chromosome but capable of recombining). By generating additional chromosome-level genome assemblies, and an improved Malassezia phylogeny, we infer that the pseudobipolar arrangement was the ancestral state of this group and revealed six independent transitions to tetrapolarity, seemingly driven by centromere fission or translocations in centromere-flanking regions. Additionally, in an approach to uncover a sexual cycle, Malassezia furfur strains were engineered to express different MAT alleles in the same cell. The resulting strains produce hyphae reminiscent of early steps in sexual development and display upregulation of genes associated with sexual development as well as others encoding lipases and a protease potentially relevant for pathogenesis of the fungus. Our study reveals a previously unseen genomic relocation of mating-type loci in fungi and provides insight toward the identification of a sexual cycle in Malassezia, with possible implications for pathogenicity.

Part 1: Understanding the role of Malassezia spp. in skin disorders: Malassezia yeasts as commensal or pathogenic organisms of human and animal skin

INTRODUCTION

Malassezia spp. are a group of lipid-dependent basidiomycetes yeasts acting as commensal organisms of the human and animal skin. However, under some not well-defined circumstances, these yeasts may switch to opportunistic pathogens triggering a number of skin disorders with different clinical presentations. The genus comprises of 18 lipid-dependent species with a variable distribution in the hosts and pathologies thus suggesting a host- and microbe-specific interactions.

AREA COVERED

This review highlighted and discussed the most recent literature regarding the genus Malassezia as a commensal or pathogenic organisms highlighting Malassezia-associated skin disorders in humans and animals and their antifungal susceptibility profile. A literature search of Malassezia associated skin disorders was performed via PubMed and Google scholar (up to May 2023), using the different keywords mainly associated with Malassezia skin disorders and Malassezia antifungal resistance.

EXPERT OPINION

Malassezia yeasts are part of the skin mycobiota and their life cycle is strictly associated with the environment in which they live. The biochemical, physiological, or immunological condition of the host skin selects Malassezia spp. or genotypes able to survive in a specific environment by changing their metabolisms, thus producing virulence factors or metabolites which can cause skin disorders with different clinical presentations.

Frequent transitions in mating-type locus chromosomal organization in Malassezia and early steps in sexual reproduction

Fungi in the basidiomycete genus Malassezia are the most prevalent eukaryotic microbes resident on the skin of human and other warm-blooded animals and have been implicated in skin diseases and systemic disorders. Analysis of Malassezia genomes revealed that key adaptations to the skin microenvironment have a direct genomic basis, and the identification of mating/meiotic genes suggests a capacity to reproduce sexually, even though no sexual cycle has yet been observed. In contrast to other bipolar or tetrapolar basidiomycetes that have either two linked mating-type-determining ( MAT ) loci or two MAT loci on separate chromosomes, in Malassezia species studied thus far the two MAT loci are arranged in a pseudobipolar configuration (linked on the same chromosome but capable of recombining). By incorporating newly generated chromosome-level genome assemblies, and an improved Malassezia phylogeny, we infer that the pseudobipolar arrangement was the ancestral state of this group and revealed six independent transitions to tetrapolarity, seemingly driven by centromere fission or translocations in centromere- flanking regions. Additionally, in an approach to uncover a sexual cycle, Malassezia furfur strains were engineered to express different MAT alleles in the same cell. The resulting strains produce hyphae reminiscent of early steps in sexual development and display upregulation of genes associated with sexual development as well as others encoding lipases and a protease potentially relevant for pathogenesis of the fungus. Our study reveals a previously unseen genomic relocation of mating-type loci in fungi and provides insight towards the discovery of a sexual cycle in Malassezia , with possible implications for pathogenicity.

Significance Statement

Malassezia , the dominant fungal group of the mammalian skin microbiome, is associated with numerous skin disorders. Sexual development and yeast-to-hyphae transitions, governed by genes at two mating-type ( MAT ) loci, are thought to be important for fungal pathogenicity. However, Malassezia sexual reproduction has never been observed. Here, we used chromosome-level assemblies and comparative genomics to uncover unforeseen transitions in MAT loci organization within Malassezia , possibly related with fragility of centromeric-associated regions. Additionally, by expressing different MAT alleles in the same cell, we show that Malassezia can undergo hyphal development and this phenotype is associated with increased expression of key mating genes along with other genes known to be virulence factors, providing a possible connection between hyphal development, sexual reproduction, and pathogenicity.

Co-evolution of large inverted repeats and G-quadruplex DNA in fungal mitochondria may facilitate mitogenome stability: the case of Malassezia

Mitogenomes are essential due to their contribution to cell respiration. Recently they have also been implicated in fungal pathogenicity mechanisms. Members of the basidiomycetous yeast genus Malassezia are an important fungal component of the human skin microbiome, linked to various skin diseases, bloodstream infections, and they are increasingly implicated in gut diseases and certain cancers. In this study, the comparative analysis of Malassezia mitogenomes contributed to phylogenetic tree construction for all species. The mitogenomes presented significant size and gene order diversity which correlates to their phylogeny. Most importantly, they showed the inclusion of large inverted repeats (LIRs) and G-quadruplex (G4) DNA elements, rendering Malassezia mitogenomes a valuable test case for elucidating the evolutionary mechanisms responsible for this genome diversity. Both LIRs and G4s coexist and convergently evolved to provide genome stability through recombination. This mechanism is common in chloroplasts but, hitherto, rarely found in mitogenomes.

Malassezia pachydermatis from brown bear: A comprehensive analysis reveals novel genotypes and distribution of all detected variants in domestic and wild animals

Malassezia pachydermatis (phylum Basidiomycota, class Malasseziomycetes) is a zoophilic opportunistic pathogen with recognized potential for invasive infections in humans. Although this pathogenic yeast is widespread in nature, it has been primarily studied in domestic animals, so available data on its genotypes in the wild are limited. In this study, 80 yeast isolates recovered from 42 brown bears (Ursus arctos) were identified as M. pachydermatis by a culture-based approach. MALDI-TOF mass spectrometry (MS) was used to endorse conventional identification. The majority of samples exhibited a high score fluctuation, with 42.5% of isolates generating the best scores in the range confident only for genus identification. However, the use of young biomass significantly improved the identification of M. pachydermatis at the species confidence level (98.8%). Importantly, the same MALDI-TOF MS efficiency would be achieved regardless of colony age if the cut-off value was lowered to ≥1.7. Genotyping of LSU, ITS1, CHS2, and β-tubulin markers identified four distinct genotypes in M. pachydermatis isolates. The most prevalent among them was the genotype previously found in dogs, indicating its transmission potential and adaptation to distantly related hosts. The other three genotypes are described for the first time in this study. However, only one of the genotypes consisted of all four loci with bear-specific sequences, indicating the formation of a strain specifically adapted to brown bears. Finally, we evaluated the specificity of the spectral profiles of the detected genotypes. MALDI-TOF MS exhibited great potential to detect subtle differences between all M. pachydermatis isolates and revealed distinct spectral profiles of bear-specific genotypes.

Position statement: Recommendations on the diagnosis and treatment of Malassezia folliculitis

Malassezia is a lipophilic yeast that is a part of the human mycobiome. Malassezia folliculitis appears when the benign colonization of the hair follicles, by the Malassezia yeasts, becomes symptomatic with pruritic papules and pustules. Although Malassezia folliculitis is common in hospital departments, diagnosing and treating it varies among dermatologists and countries. The European Academy of Dermatology and Venereology Mycology Task Force Malassezia folliculitis working group has, therefore, sought to develop these recommendations for the diagnosis and management of Malassezia folliculitis. Recommendations comprise methods for diagnosing Malassezia folliculitis, required positive findings before starting therapies and specific treatment algorithms for individuals who are immunocompetent, immunocompromised or who have compromised liver function. In conclusion, this study provides a clinical strategy for diagnosing and managing Malassezia folliculitis.

Fungal Diversity in Korean Caves and Cave-Inhabiting Bats with Attention to Pseudogymnoascus Species

Pseudogymnoascus is a psychrophilic fungus, which is a genus widely distributed in cold regions around the world. Recently, the presence of Pseudogymnoascus destructans (Pd), the causative agent of white-nose syndrome (WNS) belonging to Pseudogymnoascus, has been reported in neighboring countries of Korea. However, no investigation on Pd has been reported in Korea. In this study, cave-inhabiting bats and their habitats were investigated in terms of the diversity of cave fungi, and we tried to confirm the presence of Pd. Three caves suspected of hosting Pd were selected, and 83 environmental and 53 bat samples were collected. A total of 154 fungal strains belonging to 31 different genera were isolated, and 20 of 154 were confirmed to belong to Pseudogymnoascus. Pd-diagnostic PCR was performed to check whether Pd was present in the isolated Pseudogymnoascus, and seven positives were confirmed. However, phylogenetic analyses revealed that no isolates belonged or were closely related to the clade with Pd. Although samples were collected from limited areas, undescribed Pseudogymnoascus species were isolated, and it was confirmed that Korean isolates were distributed in various clades. In conclusion, it is hypothesized that Korean Pseudogymnoascus presents high diversity.

Yeasts of the Malassezia Genus – Recent Findings

The genus Malassezia is a medically important genus of yeasts that can colonize the skin of humans and other warm-blooded animals. The genus currently comprises 18 species of which four new species were identified recently. The most widely known species, M. pachydermatis, occurs in animals but was detected also in humans, namely at life endangering septicaemias and in prematurely born children. Proliferation of Malassezia occurs most frequently as a result of disturbances in the normal homeostasis of host immunity on the one hand and virulence of these yeasts on the other hand. The successful management of the disease depends on the therapeutic control of overgrowth of the yeasts and any concurrent bacterial infection by local or systemic anti microbial treatment, as well as, on identification and potential correction of the predisposing factors.

Malassezia: Zoonotic Implications, Parallels and Differences in Colonization and Disease in Humans and Animals

Malassezia spp. are commensals of the skin, oral/sinonasal cavity, lower respiratory and gastrointestinal tract. Eighteen species have been recovered from humans, other mammals and birds. They can also be isolated from diverse environments, suggesting an evolutionary trajectory of adaption from an ecological niche in plants and soil to the mucocutaneous ecosystem of warm-blooded vertebrates. In humans, dogs and cats, Malassezia-associated dermatological conditions share some commonalities. Otomycosis is common in companion animals but is rare in humans. Systemic infections, which are increasingly reported in humans, have yet to be recognized in animals. Malassezia species have also been identified as pathogenetic contributors to some chronic human diseases. While Malassezia species are host-adapted, some species are zoophilic and can cause fungemia, with outbreaks in neonatal intensive care wards associated with temporary colonization of healthcare worker’s hands from contact with their pets. Although standardization is lacking, susceptibility testing is usually performed using a modified broth microdilution method. Antifungal susceptibility can vary depending on Malassezia species, body location, infection type, disease duration, presence of co-morbidities and immunosuppression. Antifungal resistance mechanisms include biofilm formation, mutations or overexpression of ERG11, overexpression of efflux pumps and gene rearrangements or overexpression in chromosome 4.

Amplicon-based sequencing and co-occurence network analysis reveals notable differences of microbial community structure in healthy and dandruff scalps

Background

Dandruff is a chronic, recurring, and common scalp problem that is caused by several etiopathogeneses with complex mechanisms. Management of this condition is typically achieved via antifungal therapies. However, the precise roles played by microbiota in the development of the condition have not been elucidated. Despite their omnipresence on human scalp little is known about the co-occurrence/co-exclusion network of cutaneous microbiota.

Results

We characterized the scalp and hair surface bacterial and fungal communities of 95 dandruff-afflicted and healthy individuals residing in China. The degree distributions of co-occurrence/co-exclusion network in fungi-bacteria and bacteria-bacteria were higher in the healthy group (P < 0.0001), whereas the betweenness values are higher in the dandruff group (P < 0.01). Meanwhile, the co-occurrence/co-exclusion network among fungi-fungi and fungi-bacteria showed that compared to the healthy group, the dandruff group had more positive links (P < 0.0001). In addition, we observed that Malassezia slooffiae, Malassezia japonica and Malassezia furfur, were more abundant in the dandruff group than in the healthy group. These microbiota were co-exclusion by either multiple bacterial genera or Malassezia sp. in healthy group. The lactic acid bacteria on the scalp and hair surface, especially the genera Lactobacillus and Lactococcus, exhibit a negative correlation with multiple bacterial genera on the scalp and hair surface. Lactobacillus plantarum and Pediococcus lactis isolated on the healthy human scalp can inhibit the growth of Staphylococcus epidermidis in vitro.

Conclusions

We showed that microbial networks on scalp and hair surface with dandruff were less integrated than their healthy counterparts, with lower node degree and more positive and stronger links which were deemed to be unstable and may be more susceptible to environmental fluctuations. Lactobacillus bacteria have extensive interactions with other bacteria or fungi in the scalp and hair surface micro-ecological network and can be used as targets for improving scalp health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08534-4.

Exploring the antifungal activity and mechanism of action of Zingiberaceae rhizome extracts against Malassezia furfur

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizomes from members of Zingiberaceae have long been used in Thai traditional medicine to treat cutaneous fungal infections, including Malassezia-related skin disorders. Alpinia galanga, Curcuma longa, Zingiber cassumunar, and Zingiber officinale are particularly popular in folk remedies.

AIM OF THE STUDY

On account of the application background in traditional medicine, the present study aims to screen and determine the composition and possible mechanism of the rhizome extracts of selected Zingiberaceae and corresponding fractions against M. furfur.

MATERIALS AND METHODS

All solvent extracts (ethanol, methanol, and n-hexane) obtained from each plant were screened for anti-Malassezia activity by agar disc diffusion assay. The MIC and MFC values of the potent rhizome extract and its bioactive fraction isolated by TLC were determined using broth dilution assay followed by chemical characterization using GC-MS. The anti-Malassezia mechanism was investigated by macroscopic and microscopic observation of cells grown in the yeast phase and hyphal phase.

RESULTS

The primary screening results showed that the n-hexane extract from A. galanga possessed the most significant anti-Malassezia activity. The MIC and MFC values of this extract were in a range of 0.04-0.08 mg/mL and 0.04-0.16 mg/mL, respectively. The TLC purification of the n-hexane extract from A. galanga gave a total of nine fractions, of which only a single exhibited anti-Malassezia activity. The GC-MS analysis of the rhizome extract and the derivative fraction revealed that the major constituents were (2,6-dimethylphenyl)borate followed by a trace content of 1,8-cineol and hydrocarbons. For the antifungal mechanism of the fraction, treatments of the fraction led to morphological changes in cell size and shape, exerted massive vacuoles in yeast form, and inhibited the transition to hyphae but not likely affected chitin contents of the cell wall of M. furfur.

CONCLUSIONS

According to the results, the n-hexane extract of A. galanga rhizome exhibits promising anti-Malassezia potential. The inhibitory effect on virulent hyphal growth supports that A. galanga is a valuable source of natural antifungal agents for further pharmaceutical research.

Comparative analysis of Malassezia furfur mitogenomes and the development of a mitochondria-based typing approach

Malassezia furfur is a yeast species belonging to Malasseziomycetes, Ustilaginomycotina and Basidiomycota that is found on healthy warm-blooded animal skin, but also involved in various skin disorders like seborrheic dermatitis/dandruff and pityriasis versicolor. Moreover, Malassezia are associated with bloodstream infections, Crohn's disease and pancreatic carcinoma. Recent advances in Malassezia genomics and genetics have focused on the nuclear genome. In this work, we present the M. furfur mitochondrial (mt) genetic heterogenicity with full analysis of 14 novel and six available M. furfur mt genomes. The mitogenome analysis reveals a mt gene content typical for fungi, including identification of variable mt regions suitable for intra-species discrimination. Three of them, namely the trnK–atp6 and cox3–nad3 intergenic regions and intron 2 of the cob gene, were selected for primer design to identify strain differences. Malassezia furfur strains belonging to known genetic variable clusters, based on AFLP and nuclear loci, were assessed for their mt variation using PCR amplification and sequencing. The results suggest that these mt regions are excellent molecular markers for the typing of M. furfur strains and may provide added value to nuclear regions when assessing evolutionary relationships at the intraspecies level.

MalaSelect: A Selective Culture Medium for Malassezia Species

Malassezia species are fastidious and slow-growing yeasts in which isolation from polymicrobial samples is hampered by fast-growing microorganisms. Malassezia selective culture media are needed. Although cycloheximide is often used, some fungi, including the chief human commensal Candida albicans, are resistant to this compound. This study aimed to test whether the macrolide rapamycin could be used in combination with cycloheximide to develop a Malassezia-selective culture medium. Rapamycin susceptibility testing was performed via microdilution assays in modified Dixon against two M. furfur and five Candida spp. The MIC was the lowest concentration that reduced growth by a minimum of 90%. Rapamycin ± cycloheximide 500 mg/L was also added to FastFung solid, and yeast suspensions were inoculated and incubated for 72 h. Rapamycin MICs for Candida spp. ranged from 0.5 to 2 mg/L, except for C. krusei, for which the MIC was >32 mg/L. M. furfur stains were rapamycin-resistant. Rapamycin and cycloheximide supplementation of the FastFung medium effectively inhibited the growth of non-Malassezia yeast, including cycloheximide-resistant C. albicans and C. tropicalis. Based on our findings, this “MalaSelect” medium should be further evaluated on polymicrobial samples for Malassezia isolation and culture.

Back to the Basics: Two Approaches for the Identification and Extraction of Lipid Droplets from Malassezia pachydermatis CBS1879 and Malassezia globosa CBS7966

Malassezia spp. are lipid-dependent yeasts that have been related to skin mycobiota and dermatological and systemic diseases. Study of lipid droplets (LDs) is relevant to elucidate the unknown role of these organelles in Malassezia and to gain a broader overview of lipid metabolism in Malassezia. Here, we standardized two protocols for the analysis of LDs in M. pachydermatis and M. globosa. The first describes co-staining for confocal laser-scanning fluorescence microscopy, and the second details extraction and purification of LDs. The double stain is achieved with three different neutral lipid fluorophores, namely Nile Red, BODIPY™ 493/503, and HCS LipidTOX™ Deep Red Neutral, in combination with Calcofluor White. For LD extraction, cell wall rupture is conducted using Trichoderma harzianum enzymes and cycles of vortexing with zirconium beads. LD purification is performed in a three-step ultracentrifugation process. These standardizations will contribute to the study of the dynamics, morphology, and composition of LDs in Malassezia. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Lipid droplet fluorescence staining Basic Protocol 2: Lipid droplet extraction and purification Support Protocol: Malassezia spp. culture conditions.

Guinea pig seborrheic dermatitis model of Malassezia restricta and the utility of luliconazole

Seborrheic dermatitis (SD) is a multifactorial disease in which Malassezia restricta has been proposed as the predominant pathogenic factor. However, experimental evidence supporting this hypothesis is limited. A guinea pig SD model using a clinical isolate of M. restricta was used to elucidate the pathogenicity of M. restricta. Also, the efficacy of 1% luliconazole (LLCZ) cream, a topical imidazole derivative, against M. restricta was compared with that of a 2% ketoconazole (KCZ) cream in the same guinea pig model. Dorsal skin hairs of guinea pig were clipped and treated with M. restricta by single or repeated inoculations without occlusion. Skin manifestations were examined macroscopically and histologically. A quantitative polymerase chain reaction (PCR) assay was also performed for mycological evaluation. An inflammatory response mimicking SD occurred after repeated as well as single inoculation but not in abraded skin. The inflammation score attained its maximum on day 11 and persisted until day 52. The yeast form of the fungal elements was distributed on the surface of stratum corneum and around the follicular orifices, and an epidermal and dermal histological reaction was observed. Application of 1% LLCZ or 2% KCZ cream significantly improved the skin manifestations and decreased the quantity of M. restricta rDNA in the skin lesions. The efficacy of topical antifungal drugs suggested that M. restricta is a pathogenic factor contributing to SD.

Learning about microbial language: possible interactions mediated by microbial volatile organic compounds (VOCs) and relevance to understanding Malassezia spp. metabolism

BACKGROUND

Microorganisms synthesize and release a large diversity of small molecules like volatile compounds, which allow them to relate and interact with their environment. Volatile organic compounds (VOCs) are carbon-based compounds with low molecular weight and generally, high vapor pressure; because of their nature, they spread easily in the environment. Little is known about the role of VOCs in the interaction processes, and less is known about VOCs produced by Malassezia, a genus of yeasts that belongs to the human skin mycobiota. These yeasts have been associated with several dermatological diseases and currently, they are considered as emerging opportunistic yeasts. Research about secondary metabolites of these yeasts is limited. The pathogenic role and the molecular mechanisms involved in the infection processes of this genus are yet to be clarified. VOCs produced by Malassezia yeasts could play an important function in their metabolism; in addition, they might be involved in either beneficial or pathogenic host-interaction processes. Since these yeasts present differences in their nutritional requirements, like lipids to grow, it is possible that these variations of growth requirements also define differences in the volatile organic compounds produced in Malassezia species.

AIM OF REVIEW

We present a mini review about VOCs produced by microorganisms and Malassezia species, and hypothesize about their role in its metabolism, which would reveal clues about host-pathogen interaction.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Since living organisms inhabit a similar environment, the interaction processes occur naturally; as a result, a signal and a response from participants of these processes become important in understanding several biological behaviors. The efforts to elucidate how living organisms interact has been studied from several perspectives. An important issue is that VOCs released by the microbiota plays a key role in the setup of relationships between living micro and macro organisms. The challenge is to determine what is the role of these VOCs produced by human microbiota in commensal/pathogenic scenarios, and how these allow understanding the species metabolism. Malassezia is part of the human mycobiota, and it is implicated in commensal and pathogenic processes. It is possible that their VOCs are involved in these behavioral changes, but the knowledge about this remains overlocked. For this reason, VOCs produced by microorganisms and Malassezia spp. and their role in several biological processes are the main topic in this review.

Superficial mycoses, a matter of concern: Global and Indian scenario-an updated analysis

Superficial mycoses of skin, nails and hair are among the common fungal infections. They are caused by dermatophytes, non-dermatophyte moulds, yeasts and yeast-like fungi. Such fungal infections are widespread all over the world and are predominant in tropical as well as subtropical regions. Environmental factors, such as warm, humid and pitiable hygienic conditions, are conducive for their growth and proliferation. Although it does not cause mortality, it is known to be associated with excessive morbidity which may be psychological or physical. This affects the quality of life of the infected individuals which leads to a negative impact on their occupational, emotional and social status. Such infections are increasing on a global scale and, therefore, are of serious concern worldwide. This review article covers the global and Indian scenario of superficial mycoses taking into account the historical background, aetiological agents, prevalence, cultural and environmental factors, risk factors, pathogenesis and hygienic practices for the prevention of superficial mycoses.

Skin fungal assemblages of bats vary based on susceptibility to white-nose syndrome

Microbial skin assemblages, including fungal communities, can influence host resistance to infectious diseases. The diversity-invasibility hypothesis predicts that high-diversity communities are less easily invaded than species-poor communities, and thus diverse microbial communities may prevent pathogens from colonizing a host. To explore the hypothesis that host fungal communities mediate resistance to infection by fungal pathogens, we investigated characteristics of bat skin fungal communities as they relate to susceptibility to the emerging disease white-nose syndrome (WNS). Using a culture-based approach, we compared skin fungal assemblage characteristics of 10 bat species that differ in susceptibility to WNS across 10 eastern U.S. states. The fungal assemblages on WNS-susceptible bat species had significantly lower alpha diversity and abundance compared to WNS-resistant species. Overall fungal assemblage structure did not vary based on WNS-susceptibility, but several yeast species were differentially abundant on WNS-resistant bat species. One yeast species inhibited Pseudogymnoascus destructans (Pd), the causative agent on WNS, in vitro under certain conditions, suggesting a possible role in host protection. Further exploration of interactions between Pd and constituents of skin fungal assemblages may prove useful for predicting susceptibility of bat populations to WNS and for developing effective mitigation strategies.

External ear canal mycobiome of some rabbit breeds

The genus Malassezia is part of the normal skin mycobiota of a wide range of warm-blooded animals. In this genus, M. cuniculi is the only species described from rabbits. However, Malassezia species are rarely studied in lagomorphs. In the present study, the presence of Malassezia was assessed in samples from the external ear canal of healthy rabbits of different breeds. Cytological and culture techniques, Sanger sequencing, and Next-generation sequencing (NGS) were used to describe the ear mycobiota in the samples. Although no growth was observed in the cultured plates, cytological examination revealed the presence of round cells similar to those of Malassezia yeasts. For metagenomics analysis, the D1/D2 domain of the large subunit of the ribosomal DNA (LSU rDNA) was PCR amplified and the resulting reads were mapped against a custom-made cured database of 26S fungal sequences. NGS analysis revealed that Basidiomycota was the most abundant phylum in all the samples followed by Ascomycota. Malassezia was the most common genus presenting the highest abundance in the external ear canal. Malassezia phylotype 131 and M. cuniculi were the main sequences detected in the external auditory canal of rabbits. The study included both lop-eared and erect-eared rabbits and no differences were observed in the results when comparing both groups. This is the first attempt to study the external ear canal mycobiome of rabbits of different breeds using NGS.

LAY SUMMARY

In the present study, the presence of Malassezia was assessed in samples from the external ear canal of healthy rabbits of different breeds. Cytological and culture techniques, Sanger sequencing, and Next-generation sequencing (NGS) were used to describe the ear mycobiota in the samples.

Living in the dark: Bat caves as hotspots of fungal diversity

Bat caves are very special roosts that harbour thousands of bats of one or more species. Such sites may hold an incredible “dark fungal diversity” which is still underestimated. We explored the culturable fungal richness in the air, on bats, and in the guano in a bat cave in Brazil’s Caatinga dry forest. Fungal abundance was 683 colony-forming units (CFU) in the guano, 673 CFU in the air, and 105 CFU on the bats. Based on morphological and phylogenetic analysis of ITS, LSU, and TUB2 sequences, fungal isolates of 59 taxa belonging to 37 genera in the phyla Ascomycota (28 genera, including Aspergillus, Penicillium, Cladosporium, and Talaromyces), Basidiomycota (eight genera, including Rhodotorula and Schizophyllum), and Mucoromycota (only Rhizopus) were identified. The fungal richness in the air was 23 taxa (especially Aspergillus taxa), mainly found at 15 m and 45 m from the cave entrance; on the bodies of bats it was 36 taxa (mainly Aspergillus taxa), especially on their wing membranes (21 taxa, nine of which were exclusively found in this microhabitat); and in guano 10 fungal taxa (especially Aspergillus and Penicillium) were found. The fungal richness associated with guano (fresh and non-fresh) was similar from bats with different eating habits (insectivorous, frugivorous, and haematophagous). Sampling effort was not sufficient to reveal the total fungal taxa richness estimated. Eight (21.6%) of the 37 genera and 17 (53.1%) of the 32 identified fungal species are reported for the first time in caves. Our results highlight bat caves in Brazil as hotspots of fungal diversity, emphasizing the need to protect such special roosts.

Prevalence of Malassezia species on the skin of HIV-seropositive patients

Malassezia is a genus of lipophilic yeasts residing on the skin of warm-blooded animals. The correlation between specific species and their involvement in skin diseases has been well researched. However, only very few studies have investigated the distribution of Malassezia spp. on the healthy skin of patients infected with human immunodeficiency virus (HIV). The purpose of this work was to analyze whether the composition of Malassezia spp. isolated from the skin of the HIV-infected patients differs from that of healthy individuals. The study included a total of 96 subjects, who were divided into two equally sized groups: HIV-seropositive and HIV-seronegative. The specimens were collected from the subjects by swabbing four anatomical sites (face, chest, back, and scalp). Species were identified using phenotype-based methods, and the identification of strains isolated from the HIV-seropositive patients was confirmed by PCR sequencing of the rDNA cluster. Malassezia spp. were isolated from 33 (69%) HIV-seropositive patients and 38 (79%) healthy volunteers. It was found that men were much more likely to have their heads colonized with Malassezia spp. than women. The most prevalent species on the skin of both HIV-seropositive and HIV-seronegative individuals were Malassezia sympodialis, M. globosa, and M. furfur, albeit at different proportions in the two populations. The diversity of Malassezia spp. was the highest on the face of the HIV-seropositive patients (Shannon-Weiner Index H = 1.35) and lowest on the back of the healthy volunteers (H = 0.16). The phenotype- and molecular-based identification methods were congruent at 94.9%. It was observed a tendency that the HIV-seropositive patients had higher CD4+ cell counts, indicating higher colonization with Malassezia spp.

Survey on the Presence of Malassezia spp. in Healthy Rabbit Ear Canals

Malassezia spp. have rarely been reported in rodents and lagomorphs. In 2011, Malassezia cuniculi was described in two rabbits. Further microscopic studies showed M. cuniculi-like yeasts in more than 50% of samples from rabbits’ ear canals, but no isolation was made. The present study details the presence of Malassezia spp. and tries to typify it from ear canals of healthy rabbits. Seventy-eight half-breed rabbits from rural farms and 98 companion dwarf rabbits from northern Italy were considered. A first attempt to screen ear swabs was performed by microscopic and cultural examination on Sabouraud Glucose Agar (SGA), modified Dixon Agar (mDA) and Leeming and Notman Agar (LNA). Additionally, ear swabs from eight further microscopically positive rabbits for M. cuniculi-like cells, were used for both isolation on LNA medium and nine of its variants and for DNA extraction, PCR and sequencing. The microscopic observation of the swabs of the screened 168 rabbits highlighted the presence of yeasts in one or both of the external ear canals of 98 rabbits (58.3%). Rabbits used for meat production were more frequently diagnosed positive than pet rabbits (P = 0.001), and young ones were more often positive compared to rabbits older than 3 months (P = 0.027). No yeast growth was observed in culture. From the eight selected rabbits, Malassezia isolation failed both on LNA and on the modified mediums. Sequences of ~300 bp fragments of 18s rDNA, obtained by PCR from swabs, showed 99.9% identity with Malassezia phylotype 131 described from human ear canals. As Malassezia-like yeasts have been observed in more than half of the examined population, its colonization of ear meatus can be considered as physiological in rabbits. The results outline how much remains to be discovered on Malassezia as a component of the skin mycobiota of rabbits and that the use of the culture examination alone is not the best choice to detect Malassezia-like yeasts in rabbits.

Biology, diagnosis and treatment of Malassezia dermatitis in dogs and cats Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

The genus Malassezia is comprised of a group of lipophilic yeasts that have evolved as skin commensals and opportunistic cutaneous pathogens of a variety of mammals and birds.

OBJECTIVES

The objective of this document is to provide the veterinary community and other interested parties with current information on the ecology, pathophysiology, diagnosis, treatment and prevention of skin diseases associated with Malassezia yeasts in dogs and cats.

METHODS AND MATERIAL

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to October 2018. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) Clinical Consensus Guideline committee provided guidance and oversight for this process. The document was presented at two international meetings of veterinary dermatology societies and one international mycology workshop; it was made available for comment on the WAVD website for a period of six months. Comments were shared with the GP electronically and responses incorporated into the final document.

CONCLUSIONS AND CLINICAL IMPORTANCE

There has been a remarkable expansion of knowledge on Malassezia yeasts and their role in animal disease, particularly since the early 1990's. Malassezia dermatitis in dogs and cats has evolved from a disease of obscurity and controversy on its existence, to now being a routine diagnosis in general veterinary practice. Clinical signs are well recognised and diagnostic approaches are well developed. A range of topical and systemic therapies is known to be effective, especially when predisposing factors are identified and corrected.

Approaches for Genetic Discoveries in the Skin Commensal and Pathogenic Malassezia Yeasts

Malassezia includes yeasts belong to the subphylum Ustilaginomycotina within the Basidiomycota. Malassezia yeasts are commonly found as commensals on human and animal skin. Nevertheless, Malassezia species are also associated with several skin disorders, such as dandruff/seborrheic dermatitis, atopic eczema, pityriasis versicolor, and folliculitis. More recently, associations of Malassezia with Crohn's disease, pancreatic ductal adenocarcinoma, and cystic fibrosis pulmonary exacerbation have been reported. The increasing availability of genomic and molecular tools have played a crucial role in understanding the genetic basis of Malassezia commensalism and pathogenicity. In the present review we report genomics advances in Malassezia highlighting unique features that potentially impacted Malassezia biology and host adaptation. Furthermore, we describe the recently developed protocols for Agrobacterium tumefaciens-mediated transformation in Malassezia, and their applications for random insertional mutagenesis or targeted gene replacement strategies.

Malassezia spp. Yeasts of Emerging Concern in Fungemia

Malassezia spp. are lipid-dependent yeasts, inhabiting the skin and mucosa of humans and animals. They are involved in a variety of skin disorders in humans and animals and may cause bloodstream infections in severely immunocompromised patients. Despite a tremendous increase in scientific knowledge of these yeasts during the last two decades, the epidemiology of Malassezia spp. related to fungemia remains largely underestimated most likely due to the difficulty in the isolation of these yeasts species due to their lipid-dependence. This review summarizes and discusses the most recent literature on Malassezia spp. infection and fungemia, its occurrence, pathogenicity mechanisms, diagnostic methods, in vitro susceptibility testing and therapeutic approaches.

Towards yeast taxogenomics: lessons from novel species descriptions based on complete genome sequences

In recent years, ‘multi-omic’ sciences have affected all aspects of fundamental and applied biological research. Yeast taxonomists, though somewhat timidly, have begun to incorporate complete genomic sequences into the description of novel taxa, taking advantage of these powerful data to calculate more reliable genetic distances, construct more robust phylogenies, correlate genotype with phenotype and even reveal cryptic sexual behaviors. However, the use of genomic data in formal yeast species descriptions is far from widespread. The present review examines published examples of genome-based species descriptions of yeasts, highlights relevant bioinformatic approaches, provides recommendations for new users and discusses some of the challenges facing the genome-based systematics of yeasts.

Analysis of Malassezia Lipidome Disclosed Differences Among the Species and Reveals Presence of Unusual Yeast Lipids

Malassezia yeasts are lipid dependent and part of the human and animal skin microbiome. However, they are also associated with a variety of dermatological conditions and even cause systemic infections. How these yeasts can live as commensals on the skin and switch to a pathogenic stage has long been a matter of debate. Lipids are important cellular molecules, and understanding the lipid metabolism and composition of Malassezia species is crucial to comprehending their biology and host-microbe interaction. Here, we investigated the lipid composition of Malassezia strains grown to the stationary phase in a complex Dixon medium broth. In this study, we perform a lipidomic analysis of a subset of species; in addition, we conducted a gene prediction analysis for the detection of lipid metabolic proteins. We identified 18 lipid classes and 428 lipidic compounds. The most commonly found lipids were triglycerides (TAG), sterol (CH), diglycerides (DG), fatty acids (FAs), phosphatidylcholine (PC), phosphatidylethanolamine (PE), ceramides, cholesteryl ester (CE), sphingomyelin (SM), acylcarnitine, and lysophospholipids. Particularly, we found a low content of CEs in Malassezia furfur, atypical M. furfur, and Malassezia pachydermatis and undetectable traces of these components in Malassezia globosa, Malassezia restricta, and Malassezia sympodialis. Remarkably, uncommon lipids in yeast, like diacylglyceryltrimethylhomoserine and FA esters of hydroxyl FAs, were found in a variable concentration in these Malassezia species. The latter are bioactive lipids recently reported to have antidiabetic and anti-inflammatory properties. The results obtained can be used to discriminate different Malassezia species and offer a new overview of the lipid composition of these yeasts. We could confirm the presence and the absence of certain lipid-biosynthesis genes in specific species. Further analyses are necessary to continue disclosing the complex lipidome of Malassezia species and the impact of the lipid metabolism in connection with the host interaction.

Unambiguous identification of fungi: where do we stand and how accurate and precise is fungal DNA barcoding?

True fungi (Fungi) and fungus-like organisms (e.g. Mycetozoa, Oomycota) constitute the second largest group of organisms based on global richness estimates, with around 3 million predicted species. Compared to plants and animals, fungi have simple body plans with often morphologically and ecologically obscure structures. This poses challenges for accurate and precise identifications. Here we provide a conceptual framework for the identification of fungi, encouraging the approach of integrative (polyphasic) taxonomy for species delimitation, i.e. the combination of genealogy (phylogeny), phenotype (including autecology), and reproductive biology (when feasible). This allows objective evaluation of diagnostic characters, either phenotypic or molecular or both. Verification of identifications is crucial but often neglected. Because of clade-specific evolutionary histories, there is currently no single tool for the identification of fungi, although DNA barcoding using the internal transcribed spacer (ITS) remains a first diagnosis, particularly in metabarcoding studies. Secondary DNA barcodes are increasingly implemented for groups where ITS does not provide sufficient precision. Issues of pairwise sequence similarity-based identifications and OTU clustering are discussed, and multiple sequence alignment-based phylogenetic approaches with subsequent verification are recommended as more accurate alternatives. In metabarcoding approaches, the trade-off between speed and accuracy and precision of molecular identifications must be carefully considered. Intragenomic variation of the ITS and other barcoding markers should be properly documented, as phylotype diversity is not necessarily a proxy of species richness. Important strategies to improve molecular identification of fungi are: (1) broadly document intraspecific and intragenomic variation of barcoding markers; (2) substantially expand sequence repositories, focusing on undersampled clades and missing taxa; (3) improve curation of sequence labels in primary repositories and substantially increase the number of sequences based on verified material; (4) link sequence data to digital information of voucher specimens including imagery. In parallel, technological improvements to genome sequencing offer promising alternatives to DNA barcoding in the future. Despite the prevalence of DNA-based fungal taxonomy, phenotype-based approaches remain an important strategy to catalog the global diversity of fungi and establish initial species hypotheses.

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.

Molecular epidemiology, in vitro susceptibility and exoenzyme screening of Malassezia clinical isolates

Introduction. Malassezia folliculitis (MF) and pityriasis versicolor (PV) are common dermatoses caused by Malassezia species. Their molecular epidemiology, drug susceptibility and exoenzymes are rarely reported in China.Aim. To investigate the molecular epidemiology, drug susceptibility and enzymatic profile of Malassezia clinical isolates.Methodology. Malassezia strains were recovered from MF and PV patients and healthy subjects (HS) and identified by sequencing analysis. The minimum inhibitory concentrations (MICs) of nine antifungals (posaconazole, voriconazole, itraconazole, fluconazole, ketoconazole, miconazole, bifonazole, terbinafine and caspofungin) and tacrolimus, the interactions between three antifungals (itraconazole, ketoconazole and terbinafine) and tacrolimus, and the extracellular enzyme profile were evaluated using broth and checkerboard microdilution and the Api-Zym system, respectively.Results. Among 392 Malassezia isolates from 729 subjects (289 MF, 218 PV and 222 HS), Malassezia furfur and Malassezia globosa accounted for 67.86 and 18.88 %, respectively. M. furfur was the major species in MF and PV patients and HS. Among 60M. furfur and 50M. globosa strains, the MICs for itraconazole, posaconazole, voriconazole and ketoconazole were <1 μg ml^-1. M. furfur was more susceptible to itraconazole, terbinafine and bifonazole but tolerant to miconazole compared with M. globosa (P<0.05). Synergistic effects between terbinafine and itraconazole or between tacrolimus and itraconazole, ketoconazole or terbinafine occurred in 6, 7, 6 and 9 out of 37 strains, respectively. Phosphatases, lipases and proteases were mainly secreted in 51 isolates.Conclusions. Itraconazole, posaconazole, voriconazole and ketoconazole are theagents against which there is greatest susceptibility. Synergistic effects between terbinafine and itraconazole or tacrolimas and antifungals may be irrelevant to clinical application. Overproduction of lipases could enhance the skin inhabitation of M. furfur.

Ambient pH regulates secretion of lipases in Malassezia furfur

Malassezia is a lipophilic cutaneous commensal yeast and associated with various skin disorders. The yeast also causes bloodstream infection via intravascular catheters and can be detected even in human gut microbiota. Ambient pH is one of the major factors that affect the physiology and metabolism of several pathogenic microorganisms. Although dynamic changes of pH environment in different parts of the body is a great challenge for Malassezia to confront, the role that ambient pH plays in Malassezia is largely unknown. In this study, we investigated the impact of ambient pH on physiology and expression of lipases in M. furfur grown under different pH conditions. The yeast was able to grow in media ranging from pH 4 to 10 without morphological alteration. Elevation in pH value enhanced the extracellular lipase activity but decreased that of intracellular lipase. The qPCR results revealed that a set of functional lipase genes, LIP3-6, were constitutively expressed regardless of pH conditions or exposure time. Based on the data, we conclude that the external pH plays a promotional role in the secretion of lipases but exerts less effect on transcription of the genes and morphology in M. furfur.

Malassezia Yeasts in Veterinary Dermatology: An Updated Overview

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

Loss of centromere function drives karyotype evolution in closely related Malassezia species

Genomic rearrangements associated with speciation often result in variation in chromosome number among closely related species. Malassezia species show variable karyotypes ranging between six and nine chromosomes. Here, we experimentally identified all eight centromeres in M. sympodialis as 3-5-kb long kinetochore-bound regions that span an AT-rich core and are depleted of the canonical histone H3. Centromeres of similar sequence features were identified as CENP-A-rich regions in Malassezia furfur, which has seven chromosomes, and histone H3 depleted regions in Malassezia slooffiae and Malassezia globosa with nine chromosomes each. Analysis of synteny conservation across centromeres with newly generated chromosome-level genome assemblies suggests two distinct mechanisms of chromosome number reduction from an inferred nine-chromosome ancestral state: (a) chromosome breakage followed by loss of centromere DNA and (b) centromere inactivation accompanied by changes in DNA sequence following chromosome-chromosome fusion. We propose that AT-rich centromeres drive karyotype diversity in the Malassezia species complex through breakage and inactivation.

Occurrence of Malassezia Spp. on Healthy Human Skin

The genus Malassezia currently includes seventeen species that have been isolated from healthy and diseased human and other animal skin. Malassezia are implicated in a range of cutaneous diseases in humans: pityriasis versicolor, atopic or seborrheic dermatitis, dandruff, folliculitis and psoriasis. The outbreak of the disease depends on the interaction between the host immune system and Malassezia species. Malassezia stimulates both the cellular and humoral immune response in humans. Although Malassezia species have been associated with various dermatological diseases in people, the detailed pathological role of Malassezia remains obscured. Malassezia yeasts require lipids for their growth and therefore to a greater extent they colonize the sites with more sebaceous glands. The ecosystem on skin is complex and its balance depends on several factors. The aim of this study was to determine the presence of Malassezia yeasts in clinically normal skin of 42 healthy, randomly selected individuals of different ages. In the group of people examined, up to 30 persons (71.4 %) represented by children, adults and the elderly were positive to Malassezia yeasts. It has been shown that the back is an area with a higher incidence (66.7 %) of observed yeast compared to the head (40.5 %).

The diversity and abundance of fungi and bacteria on the healthy and dandruff affected human scalp

Dandruff is a skin condition that affects the scalp of up to half the world's population, it is characterised by an itchy, flaky scalp and is associated with colonisation of the skin by Malassezia spp. Management of this condition is typically via antifungal therapies, however the precise role of microbes in the aggravation of the condition are incompletely characterised. Here, a combination of 454 sequencing and qPCR techniques were used to compare the scalp microbiota of dandruff and non-dandruff affected Chinese subjects. Based on 454 sequencing of the scalp microbiome, the two most abundant bacterial genera found on the scalp surface were Cutibacterium (formerly Propionibacterium) and Staphylococcus, while Malassezia was the main fungal inhabitant. Quantitative PCR (qPCR) analysis of four scalp taxa (M. restricta, M. globosa, C. acnes and Staphylococcus spp.) believed to represent the bulk of the overall population was additionally carried out. Metataxonomic and qPCR analyses were performed on healthy and lesional buffer scrub samples to facilitate assessment of whether the scalp condition is associated with differential microbial communities on the sampled skin. Dandruff was associated with greater frequencies of M. restricta and Staphylococcus spp. compared with the healthy population (p<0.05). Analysis also revealed the presence of an unclassified fungal taxon that could represent a novel Malassezia species.

Long-Chain Acyl-CoA Synthetase is Associated with the Growth of Malassezia spp

The lipophilic fungal pathogen Malassezia spp. must acquire long-chain fatty acids (LCFAs) from outside the cell. To clarify the mechanism of LCFA acquisition, we investigated fatty acid uptake by this fungus and identified the long-chain acyl-CoA synthetase (ACS) gene FAA1 in three Malassezia spp.: M. globosa, M. pachydermatis, and M. sympodialis. These FAA1 genes could compensate for the double mutation of FAA1 and FAA4 in Saccharomyces cerevisiae, suggesting that Malassezia Faa1 protein recognizes exogenous LCFAs. MgFaa1p and MpFaa1p utilized a medium-chain fatty acid, lauric acid (C12:0). Interestingly, the ACS inhibitor, triacsin C, affected the activity of the Malassezia Faa1 proteins but not that of S. cerevisiae. Triacsin C also reduced the growth of M. globosa, M. pachydermatis, and M. sympodialis. These results suggest that triacsin C and its derivatives are potential compounds for the development of new anti-Malassezia drugs.

Geographical and Ethnic Differences Influence Culturable Commensal Yeast Diversity on Healthy Skin

Commensal fungi such as Malassezia, Candida, and Rhodotorula are common on healthy skin but are also associated with opportunistic invasive and superficial infections. Skin microbial community characterization has been extensively performed worldwide, with a focus on the 16S bacterial community. These studies have focused on geographically distinct or targeted cohorts with variable reported species distributions of commensal yeast species. To determine the effects of extrinsic environmental factors such as geography, climate, and ethnicity on detected healthy skin commensal yeast diversity, we compared cohorts from Singapore and Zürich, Switzerland, representative of two geographically and climatically distinct regions comprising multi-ethnic (Chinese, Malay, Indian, Caucasian) and predominantly white Caucasian cohorts, respectively, using identical skin sampling and culture methods. We chose to use a culture-based approach as cultures isolated from patients are still required for studies of pathogenicity and antifungal susceptibility. Detection of yeast species by culture-dependent and independent sequencing-based methods suggest healthy skin diversity reflects a species distribution representative of the geography, climate and ethnic background of their local populations. Culture success and species diversity was also found to be dependent on climate, with warm tropical climates favoring high positive culture rates and greater species diversity. Multilocus sequence typing data suggests some strains are geographically distinct and may be used to segregate potential disease-causing commensals. For accurate collection and characterization of skin microbial communities, it remains recommended to employ a combination of culture-dependent and sequence-based culture-independent methods. Characterization of healthy mycobiomes in geographically distinct local populations will be useful in defining the role of commensal fungi in health and disease.