Subcutaneous phaeohyphomycosis caused byExophiala spinifera

Species Diversity, Distribution, and Phylogeny of Exophiala with the Addition of Four New Species from Thailand

The genus Exophiala is an anamorphic ascomycete fungus in the family Herpotrichiellaceae of the order Chaetothyriales. Exophiala species have been classified as polymorphic black yeast-like fungi. Prior to this study, 63 species had been validated, published, and accepted into this genus. Exophiala species are known to be distributed worldwide and have been isolated in various habitats around the world. Several Exophiala species have been identified as potential agents of human and animal mycoses. However, in some studies, Exophiala species have been used in agriculture and biotechnological applications. Here, we provide a brief review of the diversity, distribution, and taxonomy of Exophiala through an overview of the recently published literature. Moreover, four new Exophiala species were isolated from rocks that were collected from natural forests located in northern Thailand. Herein, we introduce these species as E. lamphunensis, E. lapidea, E. saxicola, and E. siamensis. The identification of these species was based on a combination of morphological characteristics and molecular analyses. Multi-gene phylogenetic analyses of a combination of the internal transcribed spacer (ITS) and small subunit (nrSSU) of ribosomal DNA, along with the translation elongation factor (tef), partial β-tubulin (tub), and actin (act) genes support that these four new species are distinct from previously known species of Exophiala. A full description, illustrations, and a phylogenetic tree showing the position of four new species are provided.

Comparative Ecology of Capsular Exophiala Species Causing Disseminated Infection in Humans

Exophiala spinifera and Exophiala dermatitidis (Fungi: Chaetothyriales) are black yeast agents potentially causing disseminated infection in apparently healthy humans. They are the only Exophiala species producing extracellular polysaccharides around yeast cells. In order to gain understanding of eventual differences in intrinsic virulence of the species, their clinical profiles were compared and found to be different, suggesting pathogenic strategies rather than coincidental opportunism. Ecologically relevant factors were compared in a model set of strains of both species, and significant differences were found in clinical and environmental preferences, but virulence, tested in Galleria mellonella larvae, yielded nearly identical results. Virulence factors, i.e., melanin, capsule and muriform cells responded in opposite direction under hydrogen peroxide and temperature stress and thus were inconsistent with their hypothesized role in survival of phagocytosis. On the basis of physiological profiles, possible natural habitats of both species were extrapolated, which proved to be environmental rather than animal-associated. Using comparative genomic analyses we found differences in gene content related to lipid metabolism, cell wall modification and polysaccharide capsule production. Despite the fact that both species cause disseminated infections in apparently healthy humans, it is concluded that they are opportunists rather than pathogens.

Cutaneous and mucosal phaeohyphomycosis caused by Exophiala spinifera in a pregnant patient: case report and literature review

We report a case of mucocutaneous phaeohyphomycosis caused by Exophiala spinifera. Crusty plaques and nodules were major clinical features. Histological examination revealed brown yeast-like cells and hyphae. Mycological and molecular data identified E. spinifera as etiologic agent. Oral itraconazole was effective, which was in accordance with the results of in vitro susceptibility testing. We speculated that her pregnancy may play a role of risk factor in the infection by E. spinifera.

Massive contamination of Exophiala dermatitidis and E. phaeomuriformis in railway stations in subtropical Turkey

In order to reveal the source of contamination of opportunistic fungi, their natural habitat has to be understood. Black yeast-like fungi are abundant in man-made environments, particularly in those that are rich in toxic hydrocarbons such as railway ties. In this study, we investigated the presence of black fungi on creosote-treated oak railway ties and concrete sleepers stained with petroleum oil. Samples were collected at two central stations in Turkish cities, Mersin and Adana, and from Tarsus town station located between these two. The sample locations had subtropical climates. A total of 570 railway samples, including 320 from oak and 250 from concrete, were collected. Cotton swabs moistened with sterile physiological saline were applied to the ties and inoculated onto malt extract agar followed by incubation at 37 °C. Overall, we recovered 97 black yeast-like fungi (17.0 % positive). Sixty-three fungi (19.7 %) were collected from creosote-treated oak, whereas 34 isolates (13.6 %) were derived from concrete; the difference was significant (P = 0.05). Identification using rDNA internal transcribed spacer revealed Exophiala dermatitidis (57.7 %) and Exophiala phaeomuriformis (42.3 %). This study suggested that hydrocarbons enrich these opportunistic black yeasts. An eventual health risk is discussed.

Chronic disfiguring facial lesions in an immunocompetent patient due to Exophiala spinifera: a case report and review of literature

Exophiala spinifera is a rare fungus causing chromoblastomycosis or different types of phaeohyphomycosis (cutaneous, subcutaneous, disseminated and cyst phaeohyphomycosis). We report a case of a young male with phaeohyphomycosis due to E. spinifera, who had multiple itchy painful papular lesions disfiguring his face for 4 years. His diagnosis was delayed and had received antibacterial and antileishmanial therapy elsewhere without any improvement. While he reported to our hospital, the histopathology of the biopsy collected from the lesion demonstrated acute on chronic inflammation with granuloma formation and darkly pigmented fungal elements. The isolate grown on culture was identified as E. spinifera on the basis of morphological characters. The identification of the isolate was further confirmed by sequencing of the ITS region of ribosomal DNA. After treatment with oral itraconazole, he had marked clinical improvement.

Multiple subcutaneous cysts due to Exophiala spinifera in an immunocompetent patient

Here we report a case of a 55-year-old Indian male presenting with multiple subcutaneous cysts, which developed from painful nodules at the dorsal right wrist joint. Subsequently a painful nodule appeared on the left knee joint. Cytological examination of the knee swelling revealed a suppurative inflammatory lesion consisting of neutrophils, lymphocytes, multinucleated giant cells and few fungal elements, without involvement of the overlying skin. Exophiala spinifera was cultured (CBS 125607) and its identity was confirmed by sequencing of the internal transcribed spacer (ITS rDNA). The cysts were excised surgically, without need of additional antifungal therapy. There was no relapse during one-year follow-up and the patient was cured successfully. In vitro antifungal susceptibility testing showed that posaconazole (0.063 μg/ml) and itraconazole (0.125 μg/ml) had the highest and caspofungin (4 μg/ml) and anidulafungin (2 μg/ml) the lowest activity against this isolate. However, their clinical effectiveness in the treatment of E. spinifera infections remains to be evaluated. In this case report, we have also compiled cases of human E. spinifera mycoses which have been reported so far.

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.

Exophiala spinifera as a cause of cutaneous phaeohyphomycosis: case study and review of the literature

Exophiala spinifera has been reported as an agent of cutaneous disease 18 times in the literature. Clinical presentations of cutaneous lesions vary widely, including erythematous papules, verrucous plaques, and deep subcutaneous abscesses. The clinical distribution and course of disease are also variable, depending on the age and immune competency of the patient. Histologic appearance occurs in one of two patterns--phaeohyphomycosis or chromoblastomycosis. While E. spinifera appears to be susceptible to multiple antimicrobial agents in vitro, clinical experience with treatment modalities has been variable. Prior to the availability of sequencing methods, species identification was based on the histopathologic presentation in tissue and morphologic features of the fungus in culture. It is likely that E. spinifera cutaneous infections have been underreported due to its incorrect identification based on earlier methods. We report an additional case of E. spinifera phaeohyphomycosis, the first to be definitively identified by sequencing. In addition, we summarize the variable clinical, histopathologic, and morphologic features, as well as treatment responses described in previously reported cutaneous infections caused by E. spinifera.

Exophiala spinifera and its allies: diagnostics from morphology to DNA barcoding

Diagnostic features of morphology, physiology, serology and genetics of species belonging to the Exophiala spinifera clade (including 11 species: Exophiala oligosperma, E. spinifera, E. xenobiotica, E. jeanselmei, E. exophialae, E. nishimurae, E. bergeri, E. nigra, Rhinocladiella similis, Ramichloridium basitonum and Phaeoannellomyces elegans), comprising a large number of human-associated Exophiala species, are summarized. Several species have closely similar morphological characters and physiological profiles. Taxonomy is therefore primarily based on sequence diversity of the Internal Transcribed Spacer (ITS) region of ribosomal DNA (rDNA). Multilocus sequencing has shown that ITS is reliable for identification of the species in this clade, and is a therefore a good candidate for barcoding species of Exophiala. Species-specific fragments were searched in the ITS region of species in the Exophiala spinifera clade and can be used to design probes for diagnosis by hybridization.

Pheohyphomycosis caused by Exophiala spinifera: a rare occurrence

A 10-year-old immunocompetent boy presented with multiple, verrucous, disseminated pheohyphomycotic lesions caused by Exophiala spinifera. The patient was not responsive to combination antifungal therapy (itraconazole, terbinafine, fluconazole) and cryotherapy. As antifungal susceptibility is known to be variable for Exophiala spinifera, in vitro sensitivity testing is recommended before medical treatment. This article reviews, in brief, all cases documented so far in the English literature.

Phaéohyphomycose sous-cutanée à Exophiala spinifera chez une malade greffée rénale

INTRODUCTION

Among the dematiaceous fungi responsible for human or animal phaeohyphomycosis, the Exophiala genus is a well-known etiologic agent and presently includes nine species considered as opportunist pathogens. To our knowledge, Exophiala spinifera has been reported as causative agent of only thirteen cases of cutaneous or systemic phaeohyphomycosis. We describe some typical phaeohyphomycotic cysts.

CASE-REPORT

A 59 year-old female renal transplant recipient, treated with ciclosporine and prednisone, presented with two painless nodular and suppurative lesions of the leg, extending slowly. Histological and microbiological examinations identified Exophiala spinifera. The patient's condition improved with voriconazole treatment.

DISCUSSION

Phaeohyphomycosis is a rare but cosmopolitan mycosis found throughout the world. Immunocompromised hosts are more vulnerable to these infections and more likely to develop severe and disseminated forms of uncertain outcome. Mycological and histological findings are important to confirm the diagnosis. The prognosis is benign and complete cure is common in cutaneous and superficial forms. Treatment is not well defined, often empirical and usually relies on antifungals and/or complete surgical resection.

Case Study: Posaconazole Treatment of Disseminated Phaeohyphomycosis Due toExophiala spinifera

A 41-year-old woman with no known immunosuppression experienced a 12-year period of a relapsing phaeohyphomycosis. Despite administration of multiple courses of therapy with standard antifungals, sustained clinical remission was not achieved. A partial response was seen initially with the combination of itraconazole and flucytosine therapy, but the patient did not respond to subsequent treatment. During the patient's pregnancy, the mycosis became disseminated, with lymphadenopathy and fever, and was considered life threatening. Despite receipt of parenteral amphotericin B therapy, the patient did not show a clinical response. After premature delivery by cesarean section, treatment with oral posaconazole suspension (800 mg/day) was started. The patient's condition improved within 1 week after initiating treatment; therapy was continued for 13 months. During posaconazole treatment, the patient showed a complete clinical response, with negative results of fungal cultures.

Phaeohyphomycosis caused by Exophiala spinifera in India

The second case of phaeohyphomycosis due to Exophiala spinifera in India has been diagnosed 46 years after the initial case. The present case involved a 12-year-old female patient with no known immunocompromising conditions. She presented with multiple verrucous, well-defined plaques encompassing phaeohyphomycotic lesions of varying sizes on her face, chest, arms and thighs. Lymph node involvement in dissemination was confirmed by demonstrating pigmented fungal elements in histopathology of the left axillary node. The infection responded positively to prolonged administration of itraconazole. The original case involved a young boy and was similarly disseminated but was more severe, with bone involvement, and had a fatal outcome. It is likely that other such cases have occurred in the intervening time but have not been reported.

Subcutaneous phaeohyphomycosis on face caused by Cladophialophora bantiana

We report the case of a patient suffering from subcutaneous phaeohyphomycosis caused by Cladophialophora bantiana. The face of the upper site was involved with small, stellate, pyogranulomatous foci and low inflammation. The patient was treated by topical and systemic corticosteriod and amphotericin B. After 3 months of treatment, the patient showed good response.

Analyses of phagocytosis, evoked oxidative burst, and killing of black yeasts by human neutrophils: a tool for estimating their pathogenicity?

The pathogenicity of several dematiaceous yeasts that have, to date, rarely been isolated in humans remains unclear. Because professional phagocytes are prominent in lesions caused by dematiaceous fungi, we address this issue by comparing phagocytosis, evoked oxidative burst and killing by human neutrophils of different black yeasts in vitro. Whereas phagocytosis of all black yeasts tested and evoked oxidative burst yielded comparable results, in contrast, the degree of killing differed significantly after 5 h. Thereby, two groups could be identified; one in which strains are killed at high rates, for example, Hortaea werneckii (81 +/- 11.6%), Exophiala castellanii (96 +/- 8.6%), Phaeoannellomyces elegans (93 +/- 9.7%), Phaeococcomyces exophialae (87 +/- 8.7%), and the other in which strains are killed to a lesser degree, for example, Exophiala dermatitidis (ATCC 34100) (61 +/- 9.5%), E. dermatitidis (CBS 207.35) (66 +/- 7.5%), E. jeanselmei (50 +/- 10.5%), E. mesophila (63 +/- 11.6%), E. bergeri (63 +/- 9.1%), and E. spinifera (57 +/- 9.6%). Non-pigmented yeasts were killed at levels comparable with those at which the white mutant strain of E. dermatitidis (ATCC 44504) was killed (95 +/- 7.5%); the yeast strains tested were Candida albicans (DSM 11943) (95 +/- 4.0% killing) and Saccharomyces cerevisiae (DSM 1333) (95 +/- 10.3%). Comparison of killing rates with the observed pathogenicity of the melanized species suggests that low killing rates might indicate or even predict a high degree of invasiveness. Although previous experiments revealed that melanization conferred killing resistance on E. dermatitidis, the differences in killing rates of other dematious fungi suggest that melanization of the cell wall is in itself insufficient to confer virulence.

Multifocal subcutaneous phaeohyphomycosis caused by Phialophora verrucosa

An otherwise healthy 85-year-old woman presented with purulent multifocal subcutaneous nodules on the dorsal side of the right forearm and hand. Histopathologic examination of the biopsied specimen showed a subcutaneous granuloma with central abscess and necrosis, consistent with phaeomycotic cyst. Faint brown septate hyphae and moniliform fungal elements were found in the granuloma. Culture of the discharge grew Phialophora verrucosa. This fungus has rarely been reported as a pathogen of subcutaneous phaeohyphomycosis. Subcutaneous phaeohyphomycosis usually presents as a single lesion. In this case of multifocal lesions, initial imperfect excision seems to have caused satellite lesions. To our knowledge, this is the first report of multifocal subcutaneous phaeohyphomycosis caused by P verrucosa. The disease responded to oral itraconazole administration.

Molecular diversity, new species and antifungal susceptibilities in the Exophiala spinifera clade

Black yeasts morphologically identified as Exophiala cf. spinifera were re-analyzed on the basis of morphology, nutritional physiology and ITS rDNA sequencing data. Ribosomal small subunit (SSU) DNA sequence data confirmed that strains belonged to a clade containing the ex-type strain of E. spinifera. Variation in the Internal Transcribed Spacer (ITS) region of the rDNA was studied within this group. Five infraspecific groups were delineated. Phylogenetic analysis of the SSU rDNA data revealed that several of the strains analyzed were located at considerable evolutionary distance from the E. spinifera clade. ITS rDNA sequencing showed that the deviating strains could not be identified with any existing species. Two new species, E. attenuata and E. nishimurae, were therefore proposed. Antimycotic susceptibility data of the new species were compared with those obtained with members of the E spinifera clade.

Phialemonium curvatum infection after bone marrow transplantation

We report a case of cutaneous infection caused by Phialemonium curvatum GAMS et COOKE, 1983, after bone marrow transplantation. The genus Phialemonium was created by GAMS & MCGINNIS in 1983 including three new species: Ph. obovatum, Ph. curvatum and Ph. dimorphosporum, and represents an intermediate genus between Acremonium and Phialophora. Nowadays, the genus Phialemonium is considered to be a pheoid fungus which may cause the eventual lesions observed in pheo- and hyalohyphomycosis. Species of this genus have been described as opportunistic agents in humans and animals, mainly as a result of immunosuppression. In the present case, the patient had multiple myeloma and received an allogenic bone marrow transplant from his HLA-compatible brother. Two months after transplantation, he developed purplish and painful nodular lesions on the right ankle. Some of these lesions drained spontaneously and apparently hyaline mycelial filaments were observed, whose culture was initially identified as Acremonium sp. Subsequent studies showed that the fungus was Phialemonium curvatum. The infection was treated with amphotericin B, followed by ketoconazole. The patient was submitted to surgical debridement followed by two skin grafts to repair the bloody area. The duration of the treatment was 4 months and secondary prophylaxis with ketoconazole alone was maintained for one additional month. No recurrence was observed after discontinuation of treatment. The authors comment on the pathogenicity of the genus Phialemonium.

Subcutaneous phaeohyphomycosis: overview and case report

Phaeohyphomycosis describes a heterogenous group of mycotic infections caused by pigmented fungi. Previously uncommon to the United States, the number of case reports in the American literature has steadily increased over the past two decades. This has been attributed to the ever increasing number of immunocompromised individuals as well as an influx of immigrants from areas where these opportunistic fungi are more commonly found. The authors present a generalized overview of phaeohyphomycosis as well as a more specific breakdown and case study involving subcutaneous phaeohyphomycosis.

Mitochondrial DNA analysis of Exophiala spinifera

Restriction fragment length polymorphism (RFLP) of mitochondrial DNA (mtDNA) was examined in 36 isolates of Exophiala spinifera (8 isolates from Brazil, 9 from China, 15 from Columbia, 1 from the United States and 2 from Venezuela). E. spinifera isolates displayed a high degree of mtDNA diversity in RFLP patterns and were clustered into six genetically heterogeneous groups (Group 1 through Group 6). Isolates of Group 2 including the type strain seemed to have a worldwide distribution. RFLP patterns of E. spinifera were also distinct from those of other dematiaceous fungi, such as E. jeanselmei, E. moniliae, E. dermatitidis, Fonsecaea pedrosoi, Cladosporium carrionii and Phialophora verrucosa. These results indicate that E. spinifera may be a taxonomic complex and that RFLP patterns will be useful in the identification, typing and epidemiology of the E. spinifera variants.

Mycetoma due to Exophiala jeanselmei and Mycobacterium chelonae in a 73-year-old man with idiopathic CD4+ T lymphocytopenia

Exophiala jeanselmei and Mycobacterium chelonae were isolated from cutaneous nodules in a 73-year-old man with mycetoma of the right lower leg. Further evaluation revealed CD4+ lymphocytopenia without evidence of HIV infection. Antibodies to HIV 1/2, p24 antigen and HIV 1/2 (PCR) and reverse transcriptase activity were not detectable. The patient was not a member of any HIV risk group. He had not previously undergone therapy or suffered from immunodeficiency. This case clearly demonstrates that infections with opportunistic moulds and/or atypical mycobacteria should be taken into consideration not only in patients with classical immundeficiency diseases but also in apparently healthy patients because infection with these agents can be the first sign of underlying immunodeficiency.

Feo-hifomicose subcutânea por Exophiala jeanselmei: registro de três casos em transplantados renais

São registrados três casos de feo-hifornicose subcutânea em transplantados renais provocados pela Exophiala jeanselmei (Langeron) McGinnis et Padhye 1977, fungo demácio capaz, também, de produzir raramente eumicetoma de grãos pretos. Este fungo, segundo KWON-CHUNG & BENNETT, 1992(27) é antigenicamente muito heterogêneo, sendo identificados até o presente momento três sorotipos com subgrupos dentro de cada um deles. A feo-hifomicose subcutânea vem se tornando cada vez mais freqüente em transplantados renais, submetidos a terapêutica imunodepressora. Como a Exophiala jeanselmei já foi isolada do meio ambiente, torna-se dificil explicar a patogenia desses casos por um despertar ou reativação de processos quiescentes. Os Autores fizeram ampla revisão da literatura, registrando principalmente os casos de feo-hifomicose publicados no Brasil. Sugerem também, eventual ação fungistática da ciclosporina A sobre a Exophiala jeanselmei.

Chromoblastomycosis caused by Exophiala spinifera

Exophiala spinifera is reported as a newly recognized agent of chromoblastomycosis. This case demonstrates that infections caused by dematiaceous fungi may be variable and that a single fungus may cause more than one type of infection. Chromoblastomycosis and phaeohyphomycosis represent extremes of a continuum of infections.

Opportunistic fungal infections in immunocompromised hosts

Fungal infections in immunocompromised hosts cause major morbidity and mortality. The Candida and Aspergillus species are the most common causes, but many rarer organisms, once considered "contaminants," are being reported. The number of patients who receive immunosuppressive agents for the treatment of malignancy or for organ transplantation is increasing as well as the potential for local or disseminated fungal infections. The diagnosis of these infections is often difficult and the existing methods for treatment are often ineffective. A high degree of suspicion to identify fungal infections and to prompt initiation of treatment must be maintained if the survival rate of these patients is expected to improve.

Osteolytic phaeohyphomycosis in a German shepherd dog caused by Phialemonium obovatum

Phialemonium obovatum was found to be the cause of osteomyelitis in a German shepherd dog. Histologic examination of the biopsied material from the left tibia revealed septate, irregularly branched hyphae, swollen cells, and ovate-to-spherical cells divided by a transverse septum. The majority of the fungal elements were hyaline, but a few had lightly pigmented cell walls that had a greenish yellow tint. The presence of melanin in the cell walls of the hyphae and especially in their septa was verified by the use of the Fontana-Masson silver stain. P. obovatum formed moist, off-white-to-ochraceous, spreading colonies with a characteristic green pigment on their reverse side. The pigment was more prominent in cultures grown at 37 degrees C than in those grown at 25 degrees C. The isolate also grew at 40 degrees C. The dog isolate produced characteristic adelophialides without conspicuous collarettes and also basal septa from the creeping vegetative hyphae growing on the surface of the medium. The numerous obovate phialoconidia were smooth and one-celled.