Acute cerebral phaeohyphomycosis due to Wangiella dermatitidis accompanied by cerebrospinal fluid eosinophilia

Exophialayunnanensis and Exophialayuxiensis (Chaetothyriales, Herpotrichiellaceae), two new species of soil-inhabiting Exophiala from Yunnan Province, China

During a survey of soil fungi collected from Yunnan Province, China, two new species of Exophiala, E.yunnanensis and E.yuxiensis, were isolated from the soil of karst rocky desertification (KRD). The DNA sequences of these respective strains, including internal transcribed spacers (ITS), large subunit nuclear ribosomal RNA (LSU rRNA), partial small subunit (SSU) and β-tubulin (tub2) were sequenced and compared with those from species closely-related to Exophiala. Exophialayunnanensis differs from the phylogenetically closely related E.nagquensis and E.brunnea by its smaller aseptate conidia. Exophialayuxiensis is phylogenetically related to E.lecanii-corni, E.lavatrina and E.mali, but can be distinguished from them by its larger conidia. Full descriptions, illustrations and phylogenetic positions of E.yunnanensis and E.yuxiensis were provided.

Diagnosis and Treatment of Invasive Mold Diseases

Although invasive fungal diseases are relatively less common than superficial diseases, there has been an overall increase in their incidence. Here, I review the epidemiology, diagnosis, and treatment of invasive mold diseases (IMDs) such as aspergillosis, mucormycosis, hyalohyphomycosis, and phaeohyphomycosis. Histopathologic demonstration of tissue invasion by hyphae or recovery of mold by the culture of a specimen obtained by a sterile procedure provides definitive evidence of IMD. If IMD cannot be confirmed through invasive procedures, IMD can be diagnosed through clinical criteria such as the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Instituteof Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) definitions. For initial primary therapy of invasive aspergillosis, voriconazole or isavuconazole is recommended and lipid formulations of amphotericin B are useful primary alternatives. Echinocandins are representative antifungal agents for salvage therapy. Treatment of invasive mucormycosis involves a combination of urgent surgical debridement of involved tissues and antifungal therapy. Lipid formulations of amphotericin B are the drug of choice for initial therapy. Isavuconazole or posaconazole can be used as salvage or step-down therapy. IMDs other than aspergillosis and mucormycosis include hyalohyphomycosis and phaeohyphomycosis, for which there is no standard therapy and the treatment depends on the clinical disease and status of the patient.

Ten decadal advances in fungal biology leading towards human well-being

Fungi are an understudied resource possessing huge potential for developing products that can greatly improve human well-being. In the current paper, we highlight some important discoveries and developments in applied mycology and interdisciplinary Life Science research. These examples concern recently introduced drugs for the treatment of infections and neurological diseases; application of -OMICS techniques and genetic tools in medical mycology and the regulation of mycotoxin production; as well as some highlights of mushroom cultivaton in Asia. Examples for new diagnostic tools in medical mycology and the exploitation of new candidates for therapeutic drugs, are also given. In addition, two entries illustrating the latest developments in the use of fungi for biodegradation and fungal biomaterial production are provided. Some other areas where there have been and/or will be significant developments are also included. It is our hope that this paper will help realise the importance of fungi as a potential industrial resource and see the next two decades bring forward many new fungal and fungus-derived products.

A fatal case of Exophiala dermatitidis meningoencephalitis in an immunocompetent host: A case report and literature review

BACKGROUND

Central nervous system (CNS) infection due to Exophiala dermatitidis is rare and fatal, and primarily reported in immunocompromised patients or those with caspase recruitment domain-containing protein 9 deficiency. Herein, we describe a case of an otherwise healthy person (without underlying disease or gene deficiency) diagnosed with Exophiala dermatitidis meningoencephalitis. The patient achieved clinical remission under high-dose antifungal therapy in the first 14 months but died after 2 years of the therapy.

CASE PRESENTATION

A 15-year-old student with headache and fever was admitted to our department. Lumbar puncture showed increased cerebrospinal fluid (CSF) pressure, moderately high CSF protein levels and cell counts, and a remarkable decrease in CSF glucose and chloride. Magnetic resonance imaging of the brain revealed multiple lesions and cerebral pia mater enhancement. CSF culture confirmed E. dermatitidis infection. We administered 4-week antifungal therapy of amphotericin B, but his CSF culture remained positive. After receiving the 12-week standard dose of voriconazole (200 mg q12h), the patient's CSF culture became negative, but his condition deteriorated with intracranial lesion enlargement. We administered a high-dose voriconazole therapy (600-800 mg per day) for 12 months, which led to clinical remission. The voriconazole dose was reduced due to adverse effects including hepatic dysfunction and hypokalemia, and the disease progressed with high intracranial pressure and epileptic seizures.

CONCLUSIONS

CNS infection caused by E. dermatitidis is fatal and the most serious form of fungal infection. Initially, high-dose and long-term antifungal therapy could be effective. Gene defect and related antifungal immunodeficiency may be the most important pathogenic and lethal factor.

First Report of Environmental Isolation of Exophiala spp. in Malaysia

The opportunistic pathogen Exophiala dermatitidis has been frequently isolated from tropical regions of the world. However, there is no report of environmental isolation of Exophiala spp. from Malaysia. The information regarding the ecology of this microbe is important for a better understanding of the opportunism. This study aims to conduct a survey of natural distribution of Exophiala spp. in Malaysia. Forty-seven strains of Exophiala-like was isolated by using selective media. These isolates from the fields were molecularly identified based on the ITS region. The biochemical activity of these microbes was tested by conducting various tests, i.e. DNase test, proteinase activity, and urea hydrolysis. Overall, 22 strains of E. dermatitidis were successfully obtained and identified from burnt tree bark, oil dripped soil sample, hot spring biofilm, railway track stones, tar road contaminated with petrol hydrocarbon, drain and deep mud of Sungai Pinang besides the new discovery from pigeon droppings. A single strain of E. heteromorpha was identified from tar road contaminated with petrol hydrocarbon. Genotypes of the isolated E. dermatitidis were identified by the neighbor-joining tree and grouped into Genotype A, A2 and B. The existence of new Genotype A4 was confirmed by a similar cladogram position in both neighbor-joining and maximum likelihood tree. The survival of E. dermatitidis in the hydrocarbon contaminated environment was studied by supplying engine oil and observing the growth pattern. The results of this study suggest that the opportunistic Exophiala spp. was isolated from nutrient limited and harsh conditions in the natural environment.

The Neurotropic Black Yeast Exophiala dermatitidis Induces Neurocytotoxicity in Neuroblastoma Cells and Progressive Cell Death

The neurotropic and extremophilic black yeast Exophiala dermatitidis (Herpotrichellaceae) inhabits diverse indoor environments, in particular bathrooms, steam baths, and dishwashers. Here, we show that the selected strain, EXF-10123, is polymorphic, can grow at 37 °C, is able to assimilate aromatic hydrocarbons (toluene, mineral oil, n-hexadecane), and shows abundant growth with selected neurotransmitters (acetylcholine, gamma-aminobutyric acid, glycine, glutamate, and dopamine) as sole carbon sources. We have for the first time demonstrated the effect of E. dermatitidis on neuroblastoma cell model SH-SY5Y. Aqueous and organic extracts of E. dermatitidis biomass reduced SH-SY5Y viability by 51% and 37%, respectively. Melanized extracellular vesicles (EVs) prepared from this strain reduced viability of the SH-SY5Y to 21%, while non-melanized EVs were considerably less neurotoxic (79% viability). We also demonstrated direct interactions of E. dermatitidis with SH-SY5Y by scanning electron and confocal fluorescence microscopy. The observed invasion and penetration of neuroblastoma cells by E. dermatitidis hyphae presumably causes the degradation of most neuroblastoma cells in only three days. This may represent a so far unknown indirect or direct cause for the development of some neurodegenerative diseases such as Alzheimer’s.

Cerebral Phaeohyphomycosis Caused by Exophiala dermatitidis in a Chinese CARD9-Deficient Patient: A Case Report and Literature Review

Exophiala dermatitidis, a dematiaceous fungus typically found in decaying organic matter worldwide, is a rare cause of fungal infections. Cerebral phaeohyphomycosis is a sporadic but often fatal infection of the brain caused by E. dermatitidis. However, due to limited reports, little is known about its specific predisposing factors, clinical manifestation, and optimal treatment modality. Here, we report a clinical presentation and management of cerebral phaeohyphomycosis in a Chinese patient. An otherwise healthy, young male who was diagnosed with neck fungal lymphadenitis caused by E. dermatitidis 7 months prior and was treated with itraconazole, presented later with progressive intracranial hypertension and persistent coma. Culture of the neck lymphoid tissue produced growth of a black yeast-like fungus, which was identified as E. dermatitidis by sequencing of the ribosomal DNA internal transcribed spacer (ITS) domains. Accordingly, a cerebral biopsy was performed, and the pathological report showed mycelia and fungal granulomas. We also sequenced CARD9 in the patient and found him to be homozygous for loss-of-function mutation; his parents were heterozygous for the same mutation. This is a first case report of cerebral phaeohyphomycosis caused by E. dermatitidis in a CARD9-deficient Chinese patient. He eventually succumbed to brain herniation and severe lung infection with a poor response to therapy. Thus, previously healthy patients with unexplained invasive E. dermatitidis infection, at any age, should be tested for inherited CARD9 deficiency.

Early-Onset Invasive Infection Due to Corynespora cassiicola Associated with Compound Heterozygous CARD9 Mutations in a Colombian Patient

PURPOSE

CARD9 deficiency is an inborn error of immunity that predisposes otherwise healthy humans to mucocutaneous and invasive fungal infections, mostly caused by Candida, but also by dermatophytes, Aspergillus, and other fungi. Phaeohyphomycosis are an emerging group of fungal infections caused by dematiaceous fungi (phaeohyphomycetes) and are being increasingly identified in patients with CARD9 deficiency. The Corynespora genus belongs to phaeohyphomycetes and only one adult patient with CARD9 deficiency has been reported to suffer from invasive disease caused by C. cassiicola. We identified a Colombian child with an early-onset, deep, and destructive mucocutaneous infection due to C. cassiicola and we searched for mutations in CARD9.

METHODS

We reviewed the medical records and immunological findings in the patient. Microbiologic tests and biopsies were performed. Whole-exome sequencing (WES) was made and Sanger sequencing was used to confirm the CARD9 mutations in the patient and her family. Finally, CARD9 protein expression was evaluated in peripheral blood mononuclear cells (PBMC) by western blotting.

RESULTS

The patient was affected by a large, indurated, foul-smelling, and verrucous ulcerated lesion on the left side of the face with extensive necrosis and crusting, due to a C. cassiicola infectious disease. WES led to the identification of compound heterozygous mutations in the patient consisting of the previously reported p.Q289* nonsense (c.865C > T, exon 6) mutation, and a novel deletion (c.23_29del; p.Asp8Alafs10*) leading to a frameshift and a premature stop codon in exon 2. CARD9 protein expression was absent in peripheral blood mononuclear cells from the patient.

CONCLUSION

We describe here compound heterozygous loss-of-expression mutations in CARD9 leading to severe deep and destructive mucocutaneous phaeohyphomycosis due to C. cassiicola in a Colombian child.

Exophiala dermatitidis isolates from various sources: using alternative invertebrate host organisms (Caenorhabditis elegans and Galleria mellonella) to determine virulence

Exophiala dermatitidis causes chromoblastomycosis, phaeohyphomycosis and fatal infections of the central nervous system of patients with Asian background. It is also found in respiratory secretions from cystic fibrosis (CF) patients. In this study a variety of E. dermatitidis strains (isolates from Asia, environmental and CF) were characterized in their pathogenicity by survival analyzes using two different invertebrate host organisms, Caenorhabditis elegans and Galleria mellonella. Furthermore, the morphological development of hyphal formation was analyzed. E. dermatitidis exhibited pathogenicity in C. elegans. The virulence varied in a strain-dependent manner, but the nematodes were a limited model to study hyphal formation. Analysis of a melanin-deficient mutant (Mel-3) indicates that melanin plays a role during virulence processes in C. elegans. The strains isolated from Asian patients exhibited significantly higher virulence in G. mellonella compared to strains from other sources. Histological analyzes also revealed a higher potential of invasive hyphal growth in strains isolated from Asian patients. Interestingly, no significant difference was found in virulence between the Mel-3 mutant and their wild type counterpart during infection in G. mellonella. In conclusion, invasive hyphal formation of E. dermatitidis was associated with increased virulence. This work is the basis for future studies concerning E. dermatitidis virulence.

Ecology of the Human Opportunistic Black Yeast Exophiala dermatitidis Indicates Preference for Human-Made Habitats

Exophiala dermatitidis is an ascomycetous black yeast from the order Chaetothyriales. Its growth characteristics include the polymorphic life cycle, ability to grow at high and low temperatures, at a wide pH range, survival at high concentrations of NaCl, and survival at high UV and radioactive radiation. Exophiala dermatitidis causes deep or localized phaeohyphomycosis in immuno-compromised people worldwide and is regularly encountered in the lungs of cystic fibrosis patients. Regardless of numerous ecological studies worldwide, little is known about its natural habitat or the possible infection routes. The present review summarizes the published data on its frequency of occurrence in nature and in man-made habitats. We additionally confirmed its presence with culture-depending methods from a variety of habitats, such as glacial meltwater, mineral water, mineral-rich salt-pan mud, dishwashers, kitchens and different environments polluted with aromatic hydrocarbons. In conclusion, the frequency of its recovery was the highest in man-made indoor habitats, connected to water sources, and exposed to occasional high temperatures and oxidative stress.

Consistent high prevalence of Exophiala dermatitidis, a neurotropic opportunist, on railway sleepers

Environmental isolation of black yeasts potentially causing human disorders is essential for understanding ecology and routes of infection. Several Exophiala species show prevalence for man-made environments rich in monoaromatic compounds, such as creosote-treated or petroleum-stained railway sleepers. Ambient climatic conditions play a role in species composition in suitable habitats. Therefore, the aim of the present study was to establish the composition of Exophiala species in railway stations as a potential source of human infections in a subtropical region with evaluation of their antifungal susceptibility profiles. We examined 150 railway samples using cotton swabs moistened with sterile physiological saline. Black yeasts and relatives were selected on theirs colony morphology and identified based on ITS rDNA sequencing. Overall, 36 (24%) of samples were positive for black yeast-like fungi, i.e., Exophiala dermatitidis (n=20, 55.6%) was predominant, followed by E. phaeomuriformis (n=9, 25%), E. heteromorpha (n=5, 13.9%), and E. xenobiotica (n=2, 5.6%). Massive contaminations of E. dermatitidis were seen on railway sleepers on creosoted oak wood at the region close to the sea level, while in cold climates were primarily contaminated with clinically insignificant or rare human opportunists (E. crusticola). It seems that, high temperature and humidity are significant effect on species diversity. Moreover, the MIC results for all E. dermatitidis and E. phaeomuriformis strains revealed the widest range and the highest MICs to caspofungin (range 1-16mg/L, Geometric mean 4.912mg/L), and the lowest MIC for posaconazole (0.016-0.031mg/L, G mean 0.061mg/L). However, their clinical effectiveness in the treatment of Exophiala infections remains to be determined.

Filamentous Fungi

Filamentous mycoses are often associated with significant morbidity and mortality. Prompt diagnosis and aggressive treatment are essential for good clinical outcomes in immunocompromised patients. The host immune response plays an essential role in determining the course of exposure to potential fungal pathogens. Depending on the effectiveness of immune response and the burden of organism exposure, fungi can either be cleared or infection can occur and progress to a potentially fatal invasive disease. Nonspecific cellular immunity (i.e., neutrophils, natural killer [NK] cells, and macrophages) combined with T-cell responses are the main immunologic mechanisms of protection. The most common potential mold pathogens include certain hyaline hyphomycetes, endemic fungi, the Mucorales , and some dematiaceous fungi. Laboratory diagnostics aimed at detecting and differentiating these organisms are crucial to helping clinicians make informed decisions about treatment. The purpose of this chapter is to provide an overview of the medically important fungal pathogens, as well as to discuss the patient characteristics, antifungal-therapy considerations, and laboratory tests used in current clinical practice for the immunocompromised host.

Combination of Amphotericin B and Flucytosine against Neurotropic Species of Melanized Fungi Causing Primary Cerebral Phaeohyphomycosis

Primary central nervous system phaeohyphomycosis is a fatal fungal infection due mainly to the neurotropic melanized fungiCladophialophora bantiana,Rhinocladiella mackenziei, andExophiala dermatitidis.Despite the combination of surgery with antifungal treatment, the prognosis continues to be poor, with mortality rates ranging from 50 to 70%. Therefore, a search for a more-appropriate therapeutic approach is urgently needed. Ourin vitrostudies showed that with the combination of amphotericin B and flucytosine against these species, the median fractional inhibitory concentration (FIC) indices for strains ranged from 0.25 to 0.38, indicating synergy. By use of Bliss independence analysis, a significant degree of synergy was confirmed for all strains, with the sum ΔE ranging from 90.2 to 698.61%. No antagonism was observed. These results indicate that amphotericin B, in combination with flucytosine, may have a role in the treatment of primary cerebral infections caused by melanized fungi belonging to the orderChaetothyriales Furtherin vivostudies and clinical investigations to elucidate and confirm these observations are warranted.

Morphological and Molecular Characterization of Exophiala polymorpha sp. nov. Isolated from Sporotrichoid Lymphocutaneous Lesions in a Patient with Myasthenia Gravis

Exophiala species are capable of causing cutaneous and subcutaneous infections in immunocompromised patients. An Exophiala isolate was cultured from a biopsy specimen of a lesion on the forearm of a patient with myasthenia gravis. The patient also had lesions on the palm and distal aspects of the hand, which were successfully treated with a long-term course of itraconazole. A detailed morphological and molecular characterization of the isolate was undertaken. Phylogenetic analysis of the internal transcribed spacer region and portions of the β-tubulin and translation elongation factor 1-alpha genes indicated that the isolate was a novel species closely related to but genetically distinct from species within the Exophiala spinifera clade; the name Exophiala polymorpha sp. nov. is proposed. Morphologically, E. polymorpha most closely resembles E. xenobiotica but it differs in possessing phialides bearing prominent, wide collarettes, and it does not produce chlamydospores.

Fonsecaea pugnacius, a Novel Agent of Disseminated Chromoblastomycosis

We report a fatal case of a chromoblastomycosis-like infection caused by a novel species of Fonsecaea in a 52-year-old immunocompetent Caucasian male from an area of chromoblastomycosis endemicity in Brazil. The patient had a 30-year history of slowly evolving, verrucous lesions on the right upper arm which gradually affected the entire arm, the left hemifacial area, and the nose. Subsequent dissemination to the brain was observed, which led to death of the patient. The internal transcribed spacer (ITS) and partial large subunit (LSU), BT2, and CDC42 genes of the isolates recovered from skin and brain were sequenced, confirming the novelty of the species. The species is clinically unique in causing brain abscesses secondary to chromoblastomycosis lesions despite the apparent intact immunity of the patient. Histopathologic appearances were very different, showing muriform cells in skin and hyphae in brain.

Cerebral phaeohyphomycosis by Exophiala dermatitidis

Cerebral phaeohyphomycosis is a rare and frequently fatal disease. We report a case of cerebral phaeohyphomycosis caused by Exophiala dermatitidis in a young immuno competent male presenting to a tertiary care hospital in Jaipur.

Inherited CARD9 deficiency in 2 unrelated patients with invasive Exophiala infection

BACKGROUND

Exophiala species are mostly responsible for skin infections. Invasive Exophiala dermatitidis disease is a rare and frequently fatal infection, with 42 cases reported. About half of these cases had no known risk factors. Similarly, invasive Exophiala spinifera disease is extremely rare, with only 3 cases reported, all in patients with no known immunodeficiency. Autosomal recessive CARD9 deficiency has recently been reported in otherwise healthy patients with severe fungal diseases caused by Candida species, dermatophytes, or Phialophora verrucosa.

METHODS

We investigated an 8-year-old girl from a nonconsanguineous Angolan kindred, who was born in France and developed disseminated E. dermatitidis disease and a 26 year-old woman from an Iranian consaguineous kindred, who was living in Iran and developed disseminated E. spinifera disease. Both patients were otherwise healthy.

RESULTS

We sequenced CARD9 and found both patients to be homozygous for loss-of-function mutations (R18W and E323del). The first patient had segmental uniparental disomy of chromosome 9, carrying 2 copies of the maternal CARD9 mutated allele.

CONCLUSIONS

These are the first 2 patients with inherited CARD9 deficiency and invasive Exophiala disease to be described. CARD9 deficiency should thus be considered in patients with unexplained invasive Exophiala species disease, even in the absence of other infections.

A rare case report of subcutaneous phaeohyphomycotic cyst caused by Exophiala oligosperma in an immunocompetent host with literature review

We report a rare case of phaeohyphomycotic cyst in an immunocompetent patient caused by Exophiala oligosperma. This fungus is earlier known to cause infections in the immunocompromised. Identification of black fungi at species level is more challenging by conventional methods, and hence final identification of the fungi was based on sequencing of rDNA. The patient was managed with surgical excision. To the best of our knowledge, this is the first case report of E. oligosperma human infection from India.

Comparative genomic and transcriptomic analysis of wangiella dermatitidis, a major cause of phaeohyphomycosis and a model black yeast human pathogen

Black or dark brown (phaeoid) fungi cause cutaneous, subcutaneous, and systemic infections in humans. Black fungi thrive in stressful conditions such as intense light, high radiation, and very low pH. Wangiella (Exophiala) dermatitidis is arguably the most studied phaeoid fungal pathogen of humans. Here, we report our comparative analysis of the genome of W. dermatitidis and the transcriptional response to low pH stress. This revealed that W. dermatitidis has lost the ability to synthesize alpha-glucan, a cell wall compound many pathogenic fungi use to evade the host immune system. In contrast, W. dermatitidis contains a similar profile of chitin synthase genes as related fungi and strongly induces genes involved in cell wall synthesis in response to pH stress. The large portfolio of transporters may provide W. dermatitidis with an enhanced ability to remove harmful products as well as to survive on diverse nutrient sources. The genome encodes three independent pathways for producing melanin, an ability linked to pathogenesis; these are active during pH stress, potentially to produce a barrier to accumulated oxidative damage that might occur under stress conditions. In addition, a full set of fungal light-sensing genes is present, including as part of a carotenoid biosynthesis gene cluster. Finally, we identify a two-gene cluster involved in nucleotide sugar metabolism conserved with a subset of fungi and characterize a horizontal transfer event of this cluster between fungi and algal viruses. This work reveals how W. dermatitidis has adapted to stress and survives in diverse environments, including during human infections.

Dishwashers are a major source of human opportunistic yeast-like fungi in indoor environments in Mersin, Turkey

The natural habitat of opportunistic fungal pathogens is outside of the host; therefore, it is crucial to understand their ecology and routes of transmission. In this study, we investigated the presence of black and filamentous fungi in moist indoor environments in the city of Mersin in subtropical Turkey. In total, 177 private dwellings were screened and 893 samples obtained using cotton swabs and moistened with physiological saline from dishwashers, washing machines, refrigerators, bath-tubs, bathroom walls, and shower heads. These were then inoculated onto malt extract agar supplemented with chloramphenicol, followed by incubation at 37°C. Thirty samples (3.4%) were positive for fungi, which were then identified by sequencing the rDNA internal transcribed spacer region. Exophiala dermatitidis was the most common species (23), followed by E. phaeomuriformis (three), Magnusiomyces capitatus (two), and Candida parapsilosis (two). Genotype A of E. dermatitidis (14) was more prevalent than genotypes B (eight) and C (one) and E. phaeomuriformis was also represented by two genotypes. Our findings suggest that dishwashers are a major indoor niche for thermophilic black yeasts. The occurrence of the opportunistic filamentous fungus M. capitatus in dishwashers is consistent with a recent report.

Subcutaneous phaeohyphomycosis caused by Exophiala salmonis

We report a case of subcutaneous infection in a 55-yr-old Korean diabetic patient who presented with a cystic mass of the ankle. Black fungal colonies were observed after culturing on blood and Sabouraud dextrose agar. On microscopic observation, septated ellipsoidal or cylindrical conidia accumulating on an annellide were visualized after staining with lactophenol cotton blue. The organism was identified as Exophiala salmonis by sequencing of the ribosomal DNA internal transcribed spacer region. Phaeohyphomycosis is a heterogeneous group of mycotic infections caused by dematiaceous fungi and is commonly associated with immunocompromised patients. The most common clinical manifestations of subcutaneous lesions are abscesses or cystic masses. To the best of our knowledge, this is the first reported case in Korea of subcutaneous phaeohyphomycosis caused by E. salmonis that was confirmed by molecular analysis and identification of morphological characteristics. This case suggests that E. salmonis infections are no longer restricted to fish.

Pulmonary infection caused by Exophiala dermatitidis in a patient with multiple myeloma: A case report and a review of the literature

Exophiala dermatitidis is a dematiaceous fungus that is increasingly being identified as a cause of fungal infection especially in patients with immunodeficiency. To date, however, the factors predisposing E. dermatitidis and its optimal treatments have not been fully addressed. Here, we report the first patient with untreated multiple myeloma who developed E. dermatitidis pulmonary infection. We also review recent clinical reports describing the features of E. dermatitidis infection.

Molecular phylogenetics of exophiala species isolated from Korea

Background

Recently, identification of fungi have been supplemented by molecular tools, such as ribosomal internal transcribed spacer (ITS) sequence analysis. According to these tools, morphological Exophiala species was newly introduced or redefined.

Objective

This study was designed to investigate the phylogenetics based on ribosomal ITS sequence analysis from clinical Exophiala species isolated in Korea.

Methods

The strains of Exophiala species were 4 clinical isolates of phaeohyphomycosis agents kept in the department of dermatology, Dongguk University Medical Center(DUMC), Gyeongju, Korea. The DNAs of total 5 strains of Exophiala species were extracted by bead-beating method. Polymerase chain reaction of ITS region using the primer pairs ITS1-ITS4, was done and phylogenetic tree contributed from sequences of ITS region from 5 Korean isolates including E. dermatitidis CBS 109154 and comparative related strains deposited in GenBank.

Results

The strains of Exophiala species were 3 strains of E. dermatitidis, 1 strain of E. jeanselmei and 1 strain of Exophiala new species. Among the 3 subtypes (type A, B, C) of E. jeanselmei, E. jeanselmei DUMC 9901 belonged to type B. Of the 2 main types of E. dermatitidis (type A, B) and 3 subtypes of E. dermatitidis type A (A0, A1 and A2), two strains (E. dermatitidis CBS 709.95, E. dermatitidis CBS 109154) belonged to A0 subtypes, 1 strain (E. dermatitidis DUMC 9902) A1 subtype, respectively.

Conclusion

Phylogenetic analysis of ITS region sequence provided useful information not only for new species identification but for the subtyping and origin of Exophiala species.

Molecular typing and antifungal susceptibility of Exophiala isolates from patients with cystic fibrosis

The black yeast Exophiala dermatitidis is a frequent agent of colonization of the lungs of patients with cystic fibrosis (CF). A total of 71 clinical isolates of Exophiala from 13 patients were identified at the species level by sequencing the internal transcribed spacer (ITS) regions 1 and 2 of the rDNA genes and typed by random amplification of polymorphic DNA (RAPD), using two different primers, BG-2 and ERIC-1. In vitro susceptibility of these isolates to some systemic antifungal drugs was investigated using the CLSI method. Almost all the isolates were identified as E. dermatitidis, but long-term colonization with the closely related species E. phaeomuriformis was observed in one patient. No clustering was found according to the geographical origin of the isolates, the isolation date or the antifungal susceptibility. Variations were seen in the susceptibility of studied isolates to antifungals but most of them exhibited low susceptibility to amphotericin B and although some patients were successively colonized by two distinct genotypes, most of the isolates were distributed in patient-specific clusters. This phenomenon may be due to genomic variations of E. dermatitidis in the lung environment of CF patients. These results are typical of colonization of the airways of patients by a poorly distributed environmental fungus, which occupies particular reservoirs that need to be defined.

Waterborne Exophiala species causing disease in cold-blooded animals

The majority of mesophilic waterborne species of the black yeast genus Exophiala (Chaetothyriales) belong to a single clade judging from SSU rDNA data. Most taxa are also found to cause cutaneous or disseminated infections in cold-blooded, water animals, occasionally reaching epidemic proportions. Hosts are mainly fish, frogs, toads, turtles or crabs, all sharing smooth, moist or mucous skins and waterborne or amphibian lifestyles; occasionally superficial infections in humans are noted. Cold-blooded animals with strictly terrestrial life styles, such as reptiles and birds are missing. It is concluded that animals with moist skins, i.e. those being waterborne and those possessing sweat glands, are more susceptible to black yeast infection. Melanin and the ability to assimilate alkylbenzenes are purported general virulence factors. Thermotolerance influences the choice of host. Exophiala species in ocean water mostly have maximum growth temperatures below 30 °C, whereas those able to grow until 33(−36) °C are found in shallow waters and occasionally on humans. Tissue responses vary with the phylogenetic position of the host, the lower animals showing poor granulome formation. Species circumscriptions have been determined by multilocus analyses involving partial ITS, TEF1, BT2 and ACT1.

Melanized fungi in human disease

Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Comparative virulence of three species of Exophiala in mice

The virulence of Exophiala dermatitidis, E. oligosperma and E. xenobiotica, three of the most common members of the genus that cause human infections, was evaluated using experimental models of disseminated infection in immunocompromised mice. Exophiala dermatitidis, and to a lesser extent E. oligosperma, were the two species causing the highest mortality, while mice infected with E. xenobiotica had the lowest mortality. Tissue burden and histopathology studies demonstrated the neurotropism of E. dermatitidis, while E. oligosperma and E. xenobiotica had a limited capacity for invading brain tissue. These models could be useful for testing new therapies against Exophiala infections.

Systemic phaeohyphomycosis due to Exophiala (Wangiella) in an immunocompetent child

We report a rare case of systemic lymphadenitis and hepatic involvement due to Exophiala (Wangiella) dermatitidis in a pediatric patient. An 8-year-old immunocompetent boy with chronic fever was examined through the use of sonography and CT scan which demonstrated cervical and mesenteric lymph node enlargement and numerous small hepatic lesions. The etiologic agent was isolated by means of lymph node aspiration. The fungus was identified by its morphological characteristics and through DNA sequencing of the internal transcribed spacer region of rDNA. Despite initial amphotericin B and voriconazole therapy, the child's jaundice subsided and he died 7 months later. In addition to pathogenic aspects of Exophiala dermatitidis, the diagnostic approaches and relevant therapeutic strategies are discussed.

First autochthonous case of Rhinocladiella mackenziei cerebral abscess outside the Middle East

Cerebral phaeohyphomycosis due to Rhinocladiella mackenziei is a severe infection in the middle east, resulting in nearly 100% mortality despite the application of combined surgical and antifungal therapy and occurring occasionally in otherwise healthy patients. We report the first case of brain infection in a middle-aged male in India, where R. mackenziei is not endemic.

Rapid screening for genotypes as possible markers of virulence in the neurotropic black yeast Exophiala dermatitidis using PCR-RFLP

A simple method for fungal genotype screening was developed for the black yeast Exophiala dermatitidis based on RFLP of ribosomal ITS regions currently used as potential virulence markers. In a study set of 502 strains of the species, two main genotypes were recognized. Only 0.97% of lanes were difficult to interpret as they did not clearly present one of the expected genotypes. Twenty strains were deviating and proved to be E. spinifera after sequencing. Eight common, related species (based on SSU data) with clinical significance yielded different patterns with TaqI digestion, and thus the method is also usable for routine diagnostics.

Cerebral phaeohyphomycosis--a cure at what lengths?

Cerebral phaeohyphomycosis is a fungal infection of the brain typically caused by Cladophialophora bantiana, Exophiala dermatitidis, and Rhinocladiella mackenziei, all of which belong to the order Chaetothyriales. The disease results in black, necrotic brain tissue, black pus, and black cerebrospinal fluid. Pathogens usually reach the brain through the bloodstream or lymphatic fluid and occasionally through direct spreading or accidental inoculation. Patients can present with hemiparesis, tonic spasm, headache, fever, sensory variation, cerebral irritation, and even psychotic behavioural changes. Radiological images are characterised by ring-enhanced signs and hyperdense and hypodense lesions. Pathological features frequently include black-to-brown necrotic tissue or dark-coloured pus, granulomatous inflammation, giant cell vasculitis, and pigmented fungal elements, which are easily seen on a direct potassium hydroxide smear, a rapid method for diagnosis. Black fungi can be cultured from a biopsy specimen. Combined antifungal chemotherapy, surgical debridement, and careful immunological interventions are strongly recommended to eradicate these intractable infections.

Liver cirrhosis caused by Exophiala dermatitidis

We report a case of liver cirrhosis caused by Exophiala dermatitidis in a previously healthy child. The infecting organism was initially mistaken as capsule-deficient Cryptococcus neoformans.

Phaeohyphomycosis of the central nervous system caused by Exophiala dermatitidis in a 3-year-old immunocompetent host

An extremely rare case of cerebral phaeohyphomycosis caused by Exophiala dermatitidis is reported. We described an otherwise healthy young child whose presentation was a progressive intracranial hypertension and paraplegia, accompanied by urine retention and constipation. His blood test showed eosinophilia with the proportion of eosinophilic cell up to 28%. A computed tomography and magnetic resonance imaging of the brain and the spinal cord revealed multiple lesions. A cerebral biopsy was performed and the pathological report was cerebral phaeohyphomycosis. Cultures of the tissue and cerebrospinal fluid grew the same fungus. Extraction of genomic DNA from cultures was performed, and the DNA sequence displayed 99% sequence homologies with E dermatitidis. The patient's response to therapy was poor, and the boy died 2 months later. Our experience suggests that phaeohyphomycosis should be included in the differential diagnosis in children with multiple intracranial lesions of unknown origin and eosinophilia.

The neurotropic black yeast Exophiala dermatitidis has a possible origin in the tropical rain forest

The black yeast Exophiala dermatitidis is known as a rare etiologic agent of neurotropic infections in humans, occurring particularly in East and Southeast Asia. In search of its natural habitat, a large sampling was undertaken in temperate as well as in tropical climates. Sampling sites were selected on the basis of the origins of previously isolated strains, and on the basis of physiological properties of the species, which also determined a selective isolation protocol. The species was absent from outdoor environments in the temperate climate, but present at low abundance in comparable habitats in the tropics. Positive outdoor sites particularly included faeces of frugivorous birds and bats, in urban as well as in natural areas. Tropical fruits were found E. dermatitidis positive at low incidence. Of the human-made environments sampled, railway ties contaminated by human faeces and oily debris in the tropics were massively positive, while the known abundance of the fungus in steam baths was confirmed. On the basis of the species' oligotrophy, thermotolerance, acidotolerance, moderate osmotolerance, melanization and capsular yeast cells a natural life cycle in association with frugivorous animals in foci in the tropical rain forest, involving passage of living cells through the intestinal tract was hypothesized. The human-dominated environment may have become contaminated by ingestion of wild berries carrying fungal propagules.

Spectrum of clinically relevant Exophiala species in the United States

Numerous members of the genus Exophiala are potential agents of human and animal mycoses. The majority of these infections are cutaneous and superficial, but also fatal systemic infections are known. We re-identified 188 clinical isolates from the United States, which had a preliminary morphological identification of Exophiala species, by sequencing internal transcribed spacer (ITS) region of the rRNA. Molecular identifications of the strains were as follows, in order of frequency: 55 E. dermatitidis (29.3%), 37 E. xenobiotica (19.7%), 35 E. oligosperma (18.6%), 13 E. lecanii-corni (6.9%), 12 E. phaeomuriformis (6.4%), 7 E. jeanselmei (3.7%), 7 E. bergeri (3.7%), 6 E. mesophila (3.2%), 5 E. spinifera (2.7%), 3 Exophiala sp. 1 (1.6%), 3 E. attenuata (1.6%), 3 Phialophora europaea (1.3%), 1 E. heteromorpha (0.5%), and 1 Exophiala sp. 2 (0.5%) strains. Exophiala strains were repeatedly isolated from deep infections (39.9%) involving lung, pleural fluid, sputum, digestive organs (stomach, intestines, bile), heart, brain, spleen, bone marrow, blood, dialysis fluid, lymph node, joint, breast, middle ear, throat, and intraocular tissues. About 38.3% of the Exophiala spp. strains were agents of cutaneous infections including skin, mucous membranes, nail, and corneal epithelium lesions. The other strains caused superficial infections (0.5%, including hair) or subcutaneous infection (12.0%, including paranasal sinusitis, mycetoma, and subcutaneous cyst). The systemic infections were preponderantly caused by E. dermatitidis, E. oligosperma, E. phaeomuriformis, E. xenobiotica, and E. lecanii-corni. Strains of E. bergeri, E. spinifera, E. jeanselmei, E. mesophila, and E. attenuata mainly induced cutaneous and subcutaneous infections. Since relatively few unknown ITS motifs were encountered, we suppose that the list of opportunistic Exophiala species in temperate climates is nearing completion, but a number of species still have to be described.

Molecular cloning and characterization of WdTUP1, a gene that encodes a potential transcriptional repressor important for yeast-hyphal transitions in Wangiella (Exophiala) dermatitidis

The general transcriptional repressor Tup1p is known to influence cell development in many fungi. To determine whether the Tup1p ortholog (WdTup1p) of Wangiella dermatitidis also influences cellular development in this melanized, polymorphic human pathogen, the gene (WdTUP1) that encodes this transcription factor was isolated, sequenced and disrupted. Phylogenetic analysis showed that the WdTup1p sequence was closely related to homologues in other polymorphic, conidiogenous fungi. Disruption of WdTUP1 produced mutants (wdtup1Delta) with pronounced growth and cellular abnormalities, including slow growth on various agar media and exclusively as a filamentous morphotype in liquid media. We concluded that WdTup1p represents an important switch regulator that controls the yeast-to-filamentous growth transition. However, detailed observations of the filamentous growth of the disruption mutant showed that the hyphae produced by the wdtup1Delta mutants, unlike those of the wild-type, were arrested at a stage prior to the formation of true hyphae and subsequent conidia production.

Isolation of Exophiala dermatitidis from endotracheal aspirate of a cancer patient

Exophiala (Wangiella) dermatitidis is a melanised (darkly pigmented) yeast-like organism that has been reported from the environment and wild animals. The organism is a frequent coloniser of lungs of patients with cystic fibrosis and causes occasional disseminated phaeohyphomycosis and fungaemia. Exophiala dermatitidis is distributed worldwide, but cerebral cases are restricted to East Asia. We report a case of 54-year-old Qatari female patient with a known history of cancer, suffering from pulmonary disorder. Culture of endotracheal aspirate revealed the growth of E. dermatitidis concomitant with Candida krusei. The final diagnosis of E. dermatitidis and attribution to genotype B was achieved by sequencing the rDNA internal transcribed spacer (ITS) region. The present case concerns a pulmonary colonisation by E. dermatitidis, similar to that commonly seen in cystic fibrosis patients. For the detection of E. dermatitidis in clinical specimens culturing techniques are required. The patient finally expired with persistent cancer and C. krusei fungaemia. Review of literature and listing of E. dermatitidis cases published after 1992 show a sharp increase in clinical cases during the 1990s.