Human infections due to Malassezia spp

Anti-Malassezia Drug Candidates Based on Virulence Factors of Malassezia-Associated Diseases

Malassezia is a lipophilic unicellular fungus that is able, under specific conditions, to cause severe cutaneous and systemic diseases in predisposed subjects. This review is divided into two complementary parts. The first one discusses how virulence factors contribute to Malassezia pathogenesis that triggers skin diseases. These virulence factors include Malassezia cell wall resistance, lipases, phospholipases, acid sphingomyelinases, melanin, reactive oxygen species (ROS), indoles, hyphae formation, hydrophobicity, and biofilm formation. The second section describes active compounds directed specifically against identified virulence factors. Among the strategies for controlling Malassezia spread, this review discusses the development of aryl hydrocarbon receptor (AhR) antagonists, inhibition of secreted lipase, and fighting biofilms. Overall, this review offers an updated compilation of Malassezia species, including their virulence factors, potential therapeutic targets, and strategies for controlling their spread. It also provides an update on the most active compounds used to control Malassezia species.

Apolipoprotein E Gene Polymorphism, Serum Lipids, and Risk of Superficial Fungal Infections in Egyptian Patients - A Preliminary Case-Controlled Study

Background

Apolipoprotein E (APOE) gene isoforms have been found to affect the risk of superficial fungal infections (SFIs). However, the data only cover a few ethnicities.

Aims

The present work intended to investigate the association of APOE gene polymorphism and serum lipids with the susceptibility of SFIs among a group of Egyptian patients.

Materials and Methods

Standard laboratory methods were used to estimate the serum lipid profile, and polymerase chain reaction-restriction fragment length polymorphism was used to detect APOE gene polymorphism in deoxyribonucleic acid extracted from 150 SFI patients and an equal number of apparently healthy matched controls.

Results

Serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol were significantly higher in the studied patients than in controls. The APOE gene ε2, ε4 alleles, and ε3/4 and ε3/2 genotypes were significantly distributed in the patients than in the controls. APOE ε3/3 genotype was predominant in dermatophytosis and tinea versicolour patients, and ε3/4 genotype was predominant in candidiasis.

Conclusions

ApoE alleles ε2 and ε4, and genotypes ε2/3 and ε3/4 are linked to SFI and may be risk factors, whereas allele ε3 and genotype ε3/3 may be protective for SFI in the Egyptian population studied. The lipid profile results suggest that hyperlipidemia may provide evidence for SFI pathogenesis. However; further large-scale studies are still needed to validate our results.

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.

Immunity to Invasive Fungal Diseases

Invasive fungal diseases are rare in individuals with intact immunity. This, together with the fact that there are only a few species that account for most mycotic diseases, implies a remarkable natural resistance to pathogenic fungi. Mammalian immunity to fungi rests on two pillars, powerful immune mechanisms and elevated temperatures that create a thermal restriction zone for most fungal species. Conditions associated with increased susceptibility generally reflect major disturbances of immune function involving both the cellular and humoral innate and adaptive arms, which implies considerable redundancy in host defense mechanisms against fungi. In general, tissue fungal invasion is controlled through either neutrophil or granulomatous inflammation, depending on the fungal species. Neutrophils are critical against Candida spp. and Aspergillus spp. while macrophages are essential for controlling mycoses due to Cryptococcus spp., Histoplasma spp., and other fungi. The increasing number of immunocompromised patients together with climate change could significantly increase the prevalence of fungal diseases.

Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Malassezia restricta: An Underdiagnosed Causative Agent of Blood Culture-Negative Infective Endocarditis

BACKGROUND

Infective endocarditis (IE) is a severe disease requiring microbial identification to successfully adapt its treatment. Currently, identification of its etiological microorganism remains unresolved in 5.2% of cases. We aimed to improve IE diagnosis using an ultra-sensitive molecular technique on cardiac samples in microbiologically nondocumented (culture and conventional polymerase chain reaction [PCR]) IE (NDIE) cases.

METHODS

Cardiac samples explanted in a tertiary hospital in Lyon, France, from patients with definite IE over a 5-year period were retrospectively analyzed. NDIE was defined as Duke definite-IE associated with negative explorations including cardiac samples culture, bacterial amplification, and serologies. Ultrasensitive molecular diagnosis was achieved using the Universal Microbe Detection kit (Molzym®). Fungal identification was confirmed using 26S-rDNA and internal transcribed spacer amplifications. Fungal infection was confirmed using Grocott-Gromori staining, auto-immunohistochemistry on cardiac samples, and mannan serologies.

RESULTS

Among 88 included patients, microbial DNA was detected in all 16 NDIE cases. Bacterial taxa typical of IE etiologies were detected in 13/16 cases and Malassezia restricta in the 3 other cases. In these 3 cases, histological examination confirmed the presence of fungi pathognomonic of Malassezia that reacted with patient sera in an auto-immunohistochemistry assay and cross-reacted with Candida albicans in an indirect immunofluorescent assay.

CONCLUSIONS

M. restricta appears to be an underestimated causative agent of NDIE. Importantly, serological cross-reaction of M. restricta with C. albicans may lead to its misdiagnosis. This is of major concern since M. restricta is intrinsically resistant to echinocandins; the reference treatment for Candida-fungal IE.

Host Responses in an Ex Vivo Human Skin Model Challenged With Malassezia sympodialis

Malassezia species are a major part of the normal mycobiota and colonize mainly sebum-rich skin regions of the body. This group of fungi cause a variety of infections such as pityriasis versicolor, folliculitis, and fungaemia. In particular, Malassezia sympodialis and its allergens have been associated with non-infective inflammatory diseases such as seborrheic dermatitis and atopic eczema. The aim of this study was to investigate the host response to M. sympodialis on oily skin (supplemented with oleic acid) and non-oily skin using an ex vivo human skin model. Host-pathogen interactions were analyzed by SEM, histology, gene expression, immunoassays and dual species proteomics. The skin response to M. sympodialis was characterized by increased expression of the genes encoding β-defensin 3 and RNase7, and by high levels of S100 proteins in tissue. Supplementation of oleic acid onto skin was associated with direct contact of yeasts with keratinocytes and epidermal damage. In oily conditions, there was increased expression of IL18 but no expression of antimicrobial peptide genes in the skin’s response to M. sympodialis. In supernatants from inoculated skin plus oleic acid, TNFα, IL-6, and IL1-β levels were decreased and IL-18 levels were significantly increased.

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 %).

Tinea versicolor of the neck as side effect of topical steroids for alopecia areata

Background: Treatment of alopecia areata (AA) involves use of high potency topical corticosteroids under occlusion that, even very effective, can lead to several adverse effects. Objective: We report 10 cases of patients with AA that, after using high potency topical corticosteroids, have developed tinea versicolor of the neck area. Methods: Ten patients with AA, aged 18-38 years, were prescribed with clobetasone propionate 0.05% cream under occlusion every other day but, after 3-4 months of treatment, they returned to our facility complaining the appearance of multiple white or red-brown round or oval macules in the neck area. Results: Diagnosis of pityriasis versicolor was confirmed by direct microscopy examination of skin scrapings in 10% potassion hydroxide (KOH) solution. All patients received systemic antifungal therapy associated with the daily use of ketoconazole shampoo. Conclusion: Tinea versicolor of the neck should be included among a rare but possible side effect of prolonged application of high potency topical steroids on the scalp. These cases reinforce the importance of careful dermatologic examination and recommend preventive measures in patients with alopecia areata that are using these drugs.

Diagnostic histochemistry in non-neoplastic skin diseases

Non-neoplastic skin lesions comprise a sizable group of disorders with variable etiologies and clinical manifestations. They can be grouped into vesiculopustular dermatitides; spongiotic and psoriasiform diseases; lichenoid dermatitides; lymphoid infiltrates of the dermis; granulomatous processes; bullous disorders; vasculopathies; panniculitides; deposition disorders; and defects in maintenance of dermal connective tissue. The use of histochemical methods continues to be an indispensable adjunct to conventional microscopy in the further characterization of such lesions. This review considers that topic.

Putting It All Together to Understand the Role of Malassezia spp. in Dandruff Etiology

Dandruff is a common scalp condition causing both a discomfort and an undesired social image. Various studies dating from early 1900s have investigated the condition, but understanding of underlying mechanisms and etiology of the condition is still in its infancy. Formation of dandruff is a common but complex event which has been associated with numerous causal factors. Physiological conditions such as pH, water content, or sebum secretion are some of the host-related factors. An imbalance between these factors can disturb the physiological equilibrium of the scalp that can lead to dandruff formation. However, severity of the condition is strongly related to the lipophilic yeast of the skin microbiota, Malassezia spp. On the other hand, there are recent publications highlighting the role of other scalp microbiota members on dandruff formation. This review investigates the processes leading to the formation of dandruff to provide an etiological description of the condition, with a focus on Malassezia spp.

Evaluation of selected Indian medicinal plants for antagonistic potential against Malassezia spp. and the synergistic effect of embelin in combination with ketoconazole

The genus Malassezia comprises of extremely lipophilic yeasts secreting lipases as a vital factor for survival. They are emerging as opportunistic pathogens in medical microbiology and dermatology by causing recurring and recalcitrant infection. Combinatorial therapy is a constructive way to combat infectious diseases. In that prospect, totally 16 Indian medicinal plants were screened, among which a maximum degree of antimicrobial activity was ascertained in Embelia ribes. Subsequently embelin was identified as the bioactive principle with antagonistic potential by comparative antimicrobial assay and FTIR analysis. The MIC of embelin was determined as 400 μg/ml exhibiting ∼75% of growth inhibition. Further, a fungistatic activity based on anti-lipase potential (65-89%) of embelin has been clearly substantiated by XTT and lipase assay. In addition, embelin exhibited a synergistic effect with the antifungal drug ketoconazole (KTZ) against four different Malassezia spp. with FIC index of 0.5. Therefore, the combinations of embelin and KTZ may represent a promising therapeutic regimen to treat Malassezia infections with subjugated clinical and environmental toxicity. To the best of our knowledge, this is the first report delineating the anti-lipase activity of embelin and in vitro synergistic interaction between embelin and KTZ against Malassezia spp.

Galactofuranose antigens, a target for diagnosis of fungal infections in humans

The use of biomarkers for the detection of fungal infections is of interest to complement histopathological and culture methods. Since the production of antibodies in immunocompromised patients is scarce, detection of a specific antigen could be effective for early diagnosis. D-Galactofuranose (Galf) is the antigenic epitope in glycoconjugates of several pathogenic fungi. Since Galf is not biosynthesized by mammals, it is an attractive candidate for diagnosis of infection. A monoclonal antibody that recognizes Galf is commercialized for detection of aspergillosis. The linkage of Galf in the natural glycans and the chemical structures of the synthesized Galf-containing oligosaccharides are described in this paper. The oligosaccharides could be used for the synthesis of artificial carbohydrate-based antigens, not enough exploited for diagnosis.

D-Galactofuranose (Galf) is the unit in polysaccharides and glycoconjugates of several pathogenic fungi that is recognized by the immune system. Since Galf is not synthesized by mammals, it is an attractive candidate for diagnosis of infection. Since the production of antibodies in immunocompromised patients is scarce, detection of a specific antigen could be effective for early diagnosis. An antibody that recognizes Galf is commercialized for the detection of aspergillosis. Chemically synthesized Galf-containing oligosaccharides, reviewed in this paper, could therefore be used for the synthesis of artificial carbohydrate-based antigens and in diagnosis.

Redefinition of Genus Malenchus Andrássy, 1968 (Tylenchomorpha: Tylenchidae) with Additional Data on Ecology

Malenchus is the second specious genus in Tylenchidae. In the presented study, we examined 22 populations including 12 type/paratype species. Detailed morphology was recovered using light microscopy, scanning- and transmission- electron microscopy. All population and type slides were recorded as picture and video vouchers, which are available online. We have compared inter- or intraspecific variations and extracted taxonomically informative traits. Amended definitions of the Malenchus as well as the closely related Ottolenchus were given based on a combination of morphology and recent molecular data, and their phylogeny were analyzed in a context of Tylenchidae. Furthermore, we test different fungi and moss as a food resource of Malenchus and their feeding behavior is also discussed.

Malassezia species infection of the synovium after total knee arthroplasty surgery

Infection is a serious complication after implantation of total knee-prostheses. However, fungal infection is rarely found in periprosthetic joints, and in most reports, the infecting organism is a Candida species. This is a case report of infection after left knee total arthroplasty caused by Malassezia species. The patient is still undergoing antifungal therapy with voriconazole and is still being followed-up. To the authors’ knowledge, the present case is the first report of Malassezia species in a patient after total knee arthroplasty.

Malassezia-Can it be Ignored?

Genus Malassezia comprises of 14 species of “yeast like fungi,” 13 of which are lipophilic and 1 is nonlipophilic. They are known commensals and in predisposed individuals they commonly cause a spectrum of chronic recurrent infections. They rarely also cause serious illnesses like catheter-related blood stream infections, CAPD associated peritonitis etc., Though these fungi have been known to man for over 150 years, their fastidious nature and cumbersome culture and speciation techniques have restricted research. Since the last taxonomic revision, seven new species have been added to this genus. Their ability to evade the host immune system and virulence has increased the spectrum of the diseases caused by them. These agents have been implicated as causal agents in common diseases like atopic dermatitis recently. Though culture-based research is difficult, the new molecular analysis techniques and facilities have increased research in this field such that we can devote more attention to this genus to study in detail, their characteristics and their growing implications implications in the clinical scenario.

Mycoflora of the interdigital spaces among girl students in ahvaz, iran

BACKGROUND

Fungi have been extensively isolated and investigated from skin in various parts of the world. Determining the mycoflora of normal people is important when the role of skin is considered as a reservoir for microorganisms.

OBJECTIVES

The current study aimed to investigate the incidence of fungal flora on interdigital spaces of the human foot.

PATIENTS AND METHODS

Samples were collected from interdigital spaces of 865 girl students who lived in the dormitories of Ahvaz Jundishapur University of Medical Sciences. A part of the sample was digested with 20% KOH and screened by a light microscope for fungal elements. Another part of the sample was cultured on Sabouraud glucose agar (SGA) and SGA containing 0.05 mg/mL chloramphenicol and 0.5 mg/mL cycloheximide. The fungal colonies were identified based on morphological and microscopic characteristics and biochemical tests.

RESULTS

In the current study, out of the 865 samples, 616 (71. 2%) were positive in direct examination or culture. Of these, 267 samples (30. 9%) were positive in direct examination. The most common fungal isolates in direct test were yeast (29. 4%), followed by conidia (0. 92%), melanised hypha (0. 35%) and non-septated hyphae (0. 23%). Trichophyton mentagrophytes was isolated in one of the specimens.

CONCLUSIONS

The present study demonstrated the incidence of fungal flora on interdigital spaces of human foot. The current study results showed that fungi can survive on surfaces of skin without showing the sign of infection.

In vitro antifungal susceptibility of Malassezia furfur from bloodstream infections

Fungaemia caused by Malassezia spp. in hospitalized patients requires prompt and appropriate therapy, but standard methods for the definition of the in vitro antifungal susceptibility have not been established yet. In this study, the in vitro susceptibility of Malassezia furfur from bloodstream infections (BSIs) to amphotericin B (AMB), fluconazole (FLC), itraconazole (ITC), posaconazole (POS) and voriconazole (VRC) was assessed using the broth microdilution (BMD) method of the Clinical and Laboratory Standards Institute (CLSI) with different media such as modified Sabouraud dextrose broth (SDB), RPMI and Christensen’s urea broth (CUB). Optimal broth media that allow sufficient growth of M. furfur, and produce reliable and reproducible MICs using the CLSI BMD protocol were assessed. Thirty-six M. furfur isolates collected from BSIs of patients before and during AMB therapy, and receiving FLC prophylaxis, were tested. A good growth of M. furfur was observed in RPMI, CUB and SDB at 32 °C for 48 and 72 h. No statistically significant differences were detected between the MIC values registered after 48 and 72 h incubation. ITC, POS and VRC displayed lower MICs than FLC and AMB. These last two antifungal drugs showed higher and lower MICs, respectively, when the isolates were tested in SDB. SDB is the only medium in which it is possible to detect isolates with high FLC MICs in patients receiving FLC prophylaxis. A large number of isolates showed high AMB MIC values regardless of the media used. In conclusion, SDB might be suitable to determine triazole susceptibility. However, the media, the drug formulation or the breakpoints herein applied might not be useful for assessing the AMB susceptibility of M. furfur from BSIs.

Skin Colonization by Malassezia spp. in hospitalized neonates and infants in a tertiary care centre in North India

Malassezia, a skin colonizer, is associated with multiple skin disorders in adults, and cephalic pustulosis and folliculitis in children. It can cause fungemia in infants and neonates. The time and pattern of colonization, risk factors associated with colonization and causing fungemia in children, are not well understood. The prospective cohort study was conducted to determine the rate of Malassezia species colonization and associated factors in hospitalized neonates and infants. Consecutive 50 neonates and infants admitted in neonatal and pediatric intensive care units were studied. The skin swabs were collected on the day of admission and every fifth day, thereafter, till the patient was discharged or died. Putative risk factors for the colonization of Malassezia species were recorded. Isolates were identified by phenotypic methods and sequencing of the D1 and D2 region of rDNA. Neonates were not colonized at the time of entry in neonatal ICU or at birth. Nineteen (38 %) neonates were colonized with Malassezia species during their hospital stay. Among the infants, three (6 %) came to ICU with Malassezia colonization and 26 (52 %) acquired Malassezia during ICU stay. Mechanical ventilation, duration of hospital stay, central venous catheterization, and antifungal therapy were the significantly associated factors for colonization. Malassezia furfur was the most common species isolated from the skin of infants and neonates. Colonization by Malassezia species in infants and neonates in a hospital is not uncommon and can be a potential source of nosocomial infection.

Identification of distinct ligands for the C-type lectin receptors Mincle and Dectin-2 in the pathogenic fungus Malassezia

Various C-type lectin receptors (CLRs), including Mincle and Dectin-2, function as pattern recognition receptors and play a central role in immunity to fungal pathogens. However, the precise structures of the CLR ligands in various pathogenic fungi have yet to be completely defined. Here we report that Malassezia, an opportunistic skin fungal pathogen, is cooperatively recognized by Mincle and Dectin-2 through distinct ligands. Solvent-based fractionation revealed that Mincle and Dectin-2 recognize lipophilic and hydrophilic components of Malassezia, respectively. Mass spectrometry and nuclear magnetic resonance (NMR) revealed glyceroglycolipid and unique mannosyl fatty acids linked to mannitol as two Mincle ligands. An O-linked mannobiose-rich glycoprotein was identified as a Malassezia ligand for Dectin-2. Cytokine production in response to the Mincle ligands and the Dectin-2 ligand was abrogated in Mincle(-/-) and Dectin-2(-/-) dendritic cells, respectively. These results demonstrate that Mincle and Dectin-2 recognize distinct ligands in Malassezia to induce host immune responses.

Malassezia (pityrosporum) folliculitis

Malassezia (Pityrosporum) folliculitis is a fungal acneiform condition commonly misdiagnosed as acne vulgaris. Although often associated with common acne, this condition may persist for years without complete resolution with typical acne medications. Malassezia folliculitis results from overgrowth of yeast present in the normal cutaneous flora. Eruptions may be associated with conditions altering this flora, such as immunosuppression and antibiotic use. The most common presentation is monomorphic papules and pustules, often on the chest, back, posterior arms, and face. Oral antifungals are the most effective treatment and result in rapid improvement. The association with acne vulgaris may require combinations of both antifungal and acne medications. This article reviews and updates readers on this not uncommon, but easily missed, condition.

Bloodstream infections by Malassezia and Candida species in critical care patients

Despite being considered an emerging yeast related to immunocompromised individuals, severe infections by Malassezia furfur have not been evaluated. During a one-year survey on yeasts fungemia, 290 neonatal and 17 pediatric patients with intravascular catheters, lipid parenteral nutrition, prolonged ward stay, and surgery were enrolled. In addition, the origin of the infection was investigated by swabbing hand skin of patients, parents, and healthcare workers and medical devices. All biological specimens and swabs were cultured on Sabouraud dextrose agar and Dixon agar. The yeasts identification was based on morphological and biochemical features and by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and confirmed by sequencing the internal transcribed spacer of nuclear ribosomal DNA. A higher prevalence of M. furfur (2.1%) over Candida spp. (1.4%) caused bloodstream infections (BSIs). Twelve fungemia episodes were recorded: 2 by M. furfur in a pediatric ward and 10 in a neonatal intensive care unit (6 caused by M. furfur and 4 by Candida spp.). M. furfur was also isolated from the skin of all patients with BSIs, from the hand skin of a parent, and from an incubator surface and sheet. Patients with Candida spp. and M. furfur BSIs were successfully treated with intravenous liposomal Amphotericin B. These findings highlight the need for a more accurate etiological diagnosis in high-risk patients by adding lipid-supplemented culture media for Malassezia in the current mycological routine as the clinical features, patient management, and outcomes in both Candida and Malassezia fungemia do not differ.

Management of cosmetic embarrassment caused by Malassezia spp. with fruticose lichen Cladia using phylogenetic approach

During anti-Malassezia screening of plants by CLSI broth microdilution method, Cladia aggregata (Swartz) Nyl. (family Cladoniaceae), a fruticose lichen from Sikkim (northeast Himalayan region), has been found effective at minimum inhibitory concentrations (mg/mL) of 2.72, 0.63, and 1.28 against yeast-like fungi namely, M. furfur, M. globosa and M. sympodialis, respectively. These test pathogens are responsible for pityriasis versicolor (PV) and seborrheic dermatitis (SD) in humans. We tried to establish the reason for variable MICs against various Malassezia spp. using bioinformatical tools, thereby reducing the cost of the experimentation. This is the first report on anti-Malassezia activity of C. aggregata and thus can serve as a potential source for the development of cosmaceuticals.

Classification of Cryptococcus neoformans and yeast-like fungus isolates from pigeon droppings by colony phenotyping and ITS genotyping and their seasonal variations in Korea

Cryptococcus neoformans (C neoformans) is a frequent cause of invasive fungal disease in immunocompromised human hosts. Ninety-eight samples of pigeon droppings were collected from the pigeon shelters in Seoul, and cultured on birdseed agar (BSA) and Sabouraud dextrose agar (SDA). One hundred yeast-like colonies were selected and identified via phenotype characteristics, such as colony morphology and biochemical characteristics. This was then followed with genotyping via sequencing of the internal transcribed spacer (ITS) region. The colonies were classified into four kinds of colony color types: brown type (BrT), beige type (BeT), pink type (PT), and white type (WT). Numbers of isolated BrT, BeT, PT, and WT colonies were 22 (22%), 30 (30%), 19 (19%), and 39 (39%), respectively. All BrT colonies were identified as C neoformans. BeT were identified as 19 isolates of Cryptococcus laurentii, 10 isolates of Malassezia furfur, and 1 isolate of Cryptococcus uniguttulatus. PT was divided into two colony color types: light-PT (l-PT) and deep-PT (d-PT). Eighteen of l-PT and one of d-PT were identified as Rhodotorula glutinis and Rhodotorula mucilaginosa, respectively. WT were identified as 34 isolates of Cryptococcus guilliermondii, 3 isolates of Cryptococcus zeylanoides, 1 isolate of Cryptococcus sake, and 1 isolate of Stephanoascus ciferrii. Most strains were classified identically with the use of either phenotype or genotyping techniques, but C uniguttulatus and C sake classified by phenotyping were Pseudozyma aphidis and Cryptococcus famata by genotyping. This rapid screening technique of pathogenic yeast-like fungi by only colony characteristics is also expected to be very useful for primary yeast screening. Additionally, we investigated the seasonal variations of C neoformans and other yeast-like fungi from 379 pigeon-dropping samples that were collected from February 2011 to March 2011. We isolated 685 yeast-like fungi from the samples. Almost all C neoformans and yeast-like fungi were isolated in the fall (298 strains, 43.5%) and spring (244 strains, 35.6%). A few yeast-like fungi were isolated in winter (98 strains, 14.3%) and summer (45 strains, 6%). These results would be used as an important indicator related to epidemiology and prevention of pathogenic yeast-like fungi infections transmitted through pigeon droppings.

Fatty acid profile and influence of oxythiamine on fatty acid content in Malassezia pachydermatis, Candida albicans and Saccharomyces cerevisiae

Malassezia pachydermatis and Candida albicans are fungi involved in the skin diseases and systemic infections. The therapy of such infections is difficult due to relapses and problems with pathogen identification. In our study, we compare the fatty acids profile of M. pachydermatis, C. albicans and S. cerevisiae to identify diagnostic markers and to investigate the effect of oxythiamine (OT) on the lipid composition of these species. Total fatty acid content is threefold higher in C. albicans and M. pachydermatis compared with S. cerevisiae. These two species have also increased level of polyunsaturated fatty acids (PUFA) and decreased content of monounsaturated fatty acids (MUFA). We noted differences in the content of longer chain (>18) fatty acids between studied species (for example a lack of 20 : 1 in S. cerevisiae and 22 : 0 in M. pachydermatis and C. albicans). OT reduces total fatty acids content in M. pachydermatis by 50%. In S. cerevisiae, OT increased PUFA whereas it decreased MUFA content. In C. albicans, OT decreased PUFA and increased MUFA and SFA content. The results show that the MUFA to PUFA ratio and the fatty acid profile could be useful diagnostic tests to distinguish C. albicans, M. pachydermatis and S. cerevisiae, and OT affected the lipid metabolism of the investigated species, especially M. pachydermatis.

Granulomatous dermatitis due to Malassezia sympodialis

A 67-year-old man, with multiple skin lesions that appeared over 2 years, had biopsies that disclosed granulomatous dermatitis with associated small yeasts. The urinary antigen test results were negative for Histoplasma infection; cultures from the biopsies did not grow any fungi or other potential pathogens. The chest roentgenogram results were normal. Morphologic examination revealed features of a Malassezia species. Broad-range fungal polymerase chain reaction and DNA sequencing disclosed that the infecting fungus was Malassezia sympodialis , a lipid-dependent yeast. This report supports one other case report that Malassezia species may cause granulomatous dermatitis; in the previous case, the etiologic agent was Malassezia pachydermatis , a nonlipid-dependent species. We recommend the use of lipid-supplemented culture media for specimens from patients with granulomatous dermatitis because several Malassezia species are dependent on lipid; the absence of lipid supplementation in routine cultures likely explains the negative culture results for this patient. This, to our knowledge, is the first report of granulomatous dermatitis caused by M sympodialis.

Prevalence of Malassezia species in patients with pityriasis versicolor in Rosario, Argentina

BACKGROUND

Malassezia species are considered opportunistic yeasts of increasing clinical importance. These lipophilic yeasts are associated with various human diseases, especially pityriasis versicolor (PV), a chronic superficial scaling dermatomycosis.

AIMS

The aim of this study was to isolate, identify and analyze the distribution of the different species of Malassezia in patients with PV in Rosario city (Argentina).

METHODS

A total of 264 clinical samples were studied. Isolates were identified on the basis of microscopic observation of cells, and physiological properties, such as the presence of catalase, ability to use Tween compounds, splitting of esculin, and morphology, color and precipitate production on chromogenic agar CHROMagar-Malassezia medium (CHROMM).

RESULTS

The highest prevalence of PV in this study was observed in the 25- to 45-year-old group. No differences were found in the development of PV between sexes. The most affected areas of body were the trunk and face. Malassezia sympodialis (51%) was the most commonly isolated species, followed in frequency by M. globosa (40%), Malassezia furfur (7%), Malassezia obtusa (1%) and Malassezia slooffiae (1%).

CONCLUSIONS

The success for a correct identification of these yeasts is important to improve our knowledge about their epidemiological role in PV and also to detect the appearance of strains which are resistant to the commonly used antifungal drugs.

MALDI-TOF mass spectrometry proteomic phenotyping of clinically relevant fungi

Proteomics is particularly suitable for characterising human pathogens with high life cycle complexity, such as fungi. Protein content and expression levels may be affected by growth states and life cycle morphs and correlate to species and strain variation. Identification and typing of fungi by conventional methods are often difficult, time-consuming and frequently, for unusual species, inconclusive. Proteomic phenotypes from MALDI-TOF MS were employed as analytical and typing expression profiling of yeast, yeast-like species and strain variants in order to achieve a microbial proteomics population study. Spectra from 303 clinical isolates were generated and processed by standard pattern matching with a MALDI-TOF Biotyper (MT). Identifications (IDs) were compared to a reference biochemical-based system (Vitek-2) and, when discordant, MT IDs were verified with genotyping IDs, obtained by sequencing the 25-28S rRNA hypervariable D2 region. Spectra were converted into virtual gel-like formats, and hierarchical clustering analysis was performed for 274 Candida profiles to investigate species and strain typing correlation. MT provided 257/303 IDs consistent with Vitek-2 ones. However, amongst 26/303 discordant MT IDs, only 5 appeared "true". No MT identification was achieved for 20/303 isolates for incompleteness of database species variants. Candida spectra clustering agreed with identified species and topology of Candida albicans and Candida parapsilosis specific dendrograms. MT IDs show a high analytical performance and profiling heterogeneity which seems to complement or even outclass existing typing tools. This variability reflects the high biological complexity of yeasts and may be properly exploited to provide epidemiological tracing and infection dispersion patterns.

Antifungal activity of the aqueous extract of Ilex paraguariensis against Malassezia furfur

Malassezia furfur is a lipodependent, dimorphic and saprophyte fungus which causes pityriasis versicolor, dandruff and seborrheic dermatitis in humans. The drugs available to treat this fungal infection are few. These drugs are highly toxic and are costly when used in prolonged treatments. For these reasons, it is necessary to find new compounds to treat these infections. Ilex paraguariensis St Hilaire is a plant that grows in Argentina, Brazil and Paraguay. The aim of this study was to evaluate the effect of the aqueous extract of Ilex paraguariensis on the growth of M. furfur. High performance liquid chromatography (HPLC) was employed to identify and isolate compounds of I. paraguariensis and the agar-well diffusion method was used to assess the antifungal activity of the extract. The fungicidal/fungistatic effect was evaluated by the modified Thompson assay. The results demonstrated that the aqueous extract of Ilex paraguariensis (1000 mg/ml) possesses inhibitory activity against M. furfur. This antimalassezial activity was equivalent to 2.7 microg/ml of ketoconazole. Therefore, the topical use of Ilex paraguariensis extract as alternative antifungal agent can be suggested.

Pathogenesis of dermatophytosis and tinea versicolor

Dermatophytoses are infections caused by keratinophilic fungi known as dermatophytes. Several steps are required for infection to take place: contact, adherence, and invasion of keratin layers. The severity of the infection depends on the type of agent, environmental factors, and the host immunologic status. Tinea versicolor is caused by the Malassezia spp yeasts, which are microorganisms that belong to normal biota in seborrheic areas, but some contributing factors, such as the application of oily preparations, creams, an increase in ambient humidity, corticosteroid abuse, or genetic predisposition can induce its overgrowth in both filamentous and yeast structures. Exposure to sunlight stimulates the production of azelaic acid, which causes the appearance of hypopigmented spots. Currently, there is no scientific explanation for hyperpigmented lesions.

The cell wall galactomannan antigen from Malassezia furfur and Malassezia pachydermatis contains β-1,6-linked linear galactofuranosyl residues and its detection has diagnostic potential

Lipophilic yeasts of the genus Malassezia are associated with several skin diseases, such as pityriasis versicolor, Malassezia folliculitis, seborrhoeic dermatitis and atopic dermatitis, and are also increasingly associated with catheter-related fungaemia. The cell wall components of pathogenic micro-organisms behave as an antigen and/or ligand of the innate immune response. Live cells of Malassezia furfur and Malassezia pachydermatis did not react with an anti-α-1,2-mannoside antibody. However, they showed a strong hydrophobicity and reactivity with an anti-β-1,3-glucan antibody compared to those of C. albicans. The cell wall polysaccharides of M. furfur and M. pachydermatis were isolated and their structures analysed by 1H and 13C NMR experiments. Both polysaccharides were shown to be β-1,6-linked linear galactofuranosyl polymers with a small amount of mannan. The presence of galactomannan on cells of Malassezia species has not been described previously. The galactomannan did not react with an anti-Aspergillus fumigatus monoclonal antibody which has specificity for β-1,5-linked galactofuranosyl residues. An anti-M. furfur antibody strongly reacted with the galactomannans of M. furfur and M. pachydermatis, but did not react with the galactomannans of Trichophyton rubrum, A. fumigatus or Fonsecaea pedrosoi. The characteristics of the anti-M. furfur antibody suggest that there is potential for diagnosis of Malassezia infections by antigen detection.

[Generation of reactive oxygen species in vitro by Malassezia yeasts]

BACKGROUND AND METHODS

Free oxygen species are able to destroy cells due to their cytotoxic effect, which is based on lipid peroxidation, enzyme oxidation and protein oxidation. We analyzed the ability of six different Malassezia (M.) species to generate reactive oxygen species (ROS), using the lucigenin-amplified chemiluminescence. Further investigations showed the effect of different concentrations of terbinafine on ROS generation by M. furfur and M. pachydermatis after 10, 30 and 60 minutes.

RESULTS

All of the investigated Malassezia species (M. furfur, M. globosa, M. sympodialis, M. slooffiae, M. obtusa, M. pachydermatis) was able to generate reactive oxygen species. Terbinafine inhibited free radical production by M. furfur and M. pachydermatis.

CONCLUSION

Dependent on their cell concentrations, M. species have the ability to generate ROS. The ability of the different Malassezia species to produce ROS should be considered as one further virulence factor of this yeast. The antifungal agent terbinafine (concentrations from 100 microg to 1 microg ml -1) reduced ROS production by M. furfur and M. pachydermatis. Terbinafine acts as oxygen species scavenger. This could be an additional mechanism supporting the classic antifungal effect of this agent, the inhibition of ergosterol synthesis.

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.

Molecular detection of fungal communities in the Hawaiian marine sponges Suberites zeteki and Mycale armata

Symbiotic microbes play a variety of fundamental roles in the health and habitat ranges of their hosts. While prokaryotes in marine sponges have been broadly characterized, the diversity of sponge-inhabiting fungi has barely been explored using molecular approaches. Fungi are an important component of many marine and terrestrial ecosystems, and they may be an ecologically significant group in sponge-microbe interactions. This study tested the feasibility of using existing fungal primers for molecular analysis of sponge-associated fungal communities. None of the eight selected primer pairs yielded satisfactory results in fungal rRNA gene or internal transcribed spacer (ITS) clone library constructions. However, 3 of 10 denaturing gradient gel electrophoresis (DGGE) primer sets, which were designed to preferentially amplify fungal rRNA gene or ITS regions from terrestrial environmental samples, were successfully amplified from fungal targets in marine sponges. DGGE analysis indicated that fungal communities differ among different sponge species (Suberites zeteki and Mycale armata) and also vary between sponges and seawater. Sequence analysis of DGGE bands identified 23 and 21 fungal species from each of the two sponge species S. zeteki and M. armata, respectively. These species were representatives of 11 taxonomic orders and belonged to the phyla of Ascomycota (seven orders) and Basidiomycota (four orders). Five of these taxonomic orders (Malasseziales, Corticiales, Polyporales, Agaricales, and Dothideomycetes et Chaetothyriomcetes incertae sedis) have now been identified for the first time in marine sponges. Seven and six fungal species from S. zeteki and M. armata, respectively, are potentially new species because of their low sequence identity (< or =98%) with their references in GenBank. Phylogenetic analysis indicated sponge-derived sequences were clustered into "marine fungus clades" with those from other marine habitats. This is the first report of molecular analysis of fungal communities in marine sponges, adding depth and dimension to our understanding of sponge-associated microbial communities.