Molecular identification of melanised non-sporulating moulds: a useful tool for studying the epidemiology of phaeohyphomycosis

Osteoarticular Mycoses

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Dematiaceous fungal infections in solid organ transplantation: systematic review and bayesian meta-analysis

BACKGROUND

Dematiaceous fungi cause a number of infectious syndromes referred to as phaeohyphomycosis among both immunocompetent and immunocompromised hosts. We performed a systematic review to characterize these infections in solid organ transplant recipients (SOTR).

METHODS

We searched PubMed database (last searched 1/6/2022) for English-language reports on dematiaceous fungal infections in SOTR. Included reports needed individualized demographic, treatment, and outcome data; pediatric reports were excluded. A universally applicable bias assessment was performed on reports. Models for infection type and outcome were created using the Bayesian paradigm.

RESULTS

We included 149 reports on 201 cases of dematiaceous fungal infections in SOTR. The mean age was 54 years, 72% were men, and kidney recipients accounted for 61% of cases. Skin and soft tissue infection (SSTI) was the most common infectious syndrome (73%). Death from infection occurred in 7% of cases (14/201), with disseminated (32%) cases having the highest mortality. Our model for infection type predicted the relative probability of central nervous system infection to be highest in liver recipients. Across all transplant types, higher relative probabilities of disseminated and pulmonary infections occur in the early post-transplant period, and the predicted probabilities for these infection types decreased after 100 months post-transplantation.

DISCUSSION

We identified SSTI as the most common dematiaceous fungal infections in SOTR. Disseminated infections carried the worst prognosis. The evidence in this review is limited by the heterogeneity of included cases. No funding source was used, and this review's protocol was not registered. This article is protected by copyright. All rights reserved.

Retrospective study of phaeohyphomycosis in aquarium-housed fish, with first descriptions of Exophiala lecanii-corni and Neodevriesia cladophorae in fish

A broadening fish host range is affected by novel and known pigmented fungal pathogens. A review of 2,250 piscine submissions received by the Aquatic Pathology Service, University of Georgia, revealed 47 phaeohyphomycosis cases (2.1%), representing 34 bony and cartilaginous fish species. The majority involved bony fish (45/47, 95.7%) and were predominantly marine (41/47, 87.2%), with only a few freshwater species (4/47, 8.5%). Cartilaginous fish cases included two zebra sharks (Stegostoma fasciatum) (2/47, 4.3%). Northern seahorses (Hippocampus erectus) had the highest incidence overall (7/47, 14.9%). Culture and sequencing of the internal-transcribed spacer region of the rDNA (ITS), large ribosomal subunit gene D1/D2 domains (LSU) and the DNA polymerase II gene (RPB2) were performed for fungal identification when fresh tissue was obtainable. Exophiala, Ochroconis and Neodevriesia spp. were identified, with Exophiala as the most common fungal genus (8/11, 72.7%). Exophiala lecanii-corni and Neodevriesia cladophorae were described for the first time from fish. Microscopically, lesions were characterized by necrosis, granulomatous inflammation and angioinvasion most frequently affecting the skin/fin, skeletal muscle and kidneys. In this study of diverse aquarium-housed fish species, phaeohyphomycosis cases occurred sporadically and in rare outbreaks with variable pathologic presentations, tissue distributions and severities.

A Case of Black Fungal Keratitis Caused by Biatriospora mackinnonii

PURPOSE

To report a novel case of fungal keratitis caused by Biatriospora mackinnonii (Pyrenochaeta mackinnonii), a dematiaceous fungus (black fungus) that rarely causes dermatological infection, in a patient treated for ocular cicatricial pemphigoid.

METHODS

An 81-year-old patient with ocular cicatricial pemphigoid was referred to our hospital because of persistent corneal epithelial defects in his left eye. On examination, a slightly elevated dark lesion in the middle of the erosion and hypopyon was observed in that eye, with smear examination of the obtained specimen revealed a filamentous fungal-like material. Initially, treatment included miconazole and fluconazole ophthalmic solution eye drops, natamycin ophthalmic ointment, and systemic voriconazole, followed surgical scraping of the mass, an anterior chamber lavage, and a subconjunctival injection of miconazole. However, the focus had resistance to the treatment and finally led to corneal perforation; hence, therapeutic penetrating keratoplasty (PKP) was subsequently performed.

RESULTS

Mycological testing revealed that the lesions were Candida parapsiliosis and black fungus, with the black fungus classified as B. mackinnonii via DNA sequencing of the internal transcribed spacer and the D1/D2 domains of the 28S rRNA gene. Fungal keratitis caused by B. mackinnonii was resistant to the antifungal drugs, yet was ameliorated by PKP, with no recurrence of fungal keratitis for more than 2 years postoperative.

CONCLUSIONS

To the best of our knowledge, this is the first reported case of fungal keratitis caused by B. mackinnonii; however, in this case, PKP surgery resulted in a favorable outcome.

Deep cutaneous fungal infection by Pleosporales: An exceptional pathogen in tropical Taiwan

Deep cutaneous fungal infections (DCFI) are cutaneous and subcutaneous infectious diseases caused by fungi. Multiple genera of pathogenic fungi have been reported to cause DCFI. Herein, we report three rare cases of Pleosporales deep cutaneous infection in a southern Taiwan medical center. We evaluated the clinical manifestations, histopathological findings, pathogens, treatments and outcomes. The patients were a 77-year-old woman, a 78-year-old woman and an 81-year-old man, who lived in rural tropical areas. The lesions were erythematous noduloplaques with dark spots located on the upper extremities. Sequence-based identification showed three different fungi of the order Pleosporales, namely Nigrograna mackinnonii, Medicopsis romeroi and Parathyridaria percutanea. All three cases received 200 mg of oral itraconazole daily for 10, 2 and 8 months, respectively. Two of them are free of diseases to date, and one improved partially but did not complete the treatment. Molecular tools are helpful for the identification of DCFI to exact species, which is key to successful treatment.

Simultaneous coccidioidomycosis and phaeohyphomycosis in a kidney transplant recipient: A case report and literature review

Advances in solid organ transplantation have improved the survival of end-stage organ disease at the expense of an increased risk for opportunistic infections. Unusual clinical presentations and the possibility of concurrent infections make diagnosing invasive fungal infection (IFI) more difficult. Here, we present a case of simultaneous vertebral infection caused by Coccidioides immitis-posadasii and subcutaneous phaeohyphomycosis due to Nigrograna mackinnonii in a kidney transplant recipient. The diagnosis of both infections required invasive procedures to obtain tissue and a high index of suspicion that more than one IFI could be present. A multidisciplinary team approach for the management of immunocompromised patients with suspected or diagnosed IFI is warranted.

Long-Term Carriage of Medicopsis romeroi, an Agent of Black-Grain Mycetoma, Presenting as Phaeohyphomycosis in a Renal Transplant Patient

Medicopsis species are rare fungal pathogens that frequently resist common antifungal therapies and are difficult to identify morphologically as conidia are produced in pycnidia, a key feature of coelomycetes. Immunocompromised patients are at risk of these infections, even after remote exposure, and typically present with phaeohyphomycoses without dissemination. We present the case of a renal transplant recipient 6.5 years post-transplant who developed a slowly progressive soft tissue infection mimicking a synovial cyst. A cultured isolate was identified as Medicopsis romeroi by sequencing of multiple ribosomal loci. The patient responded well to debridement and posaconazole therapy. Solid-organ transplant patients are at risk of opportunistic fungal infection long after transplant, and molecular methods are often required for definitive identification.

The Phytopathogenic Fungus Pallidocercospora crystallina-Caused Localized Subcutaneous Phaeohyphomycosis in a Patient with a Homozygous Missense CARD9 Mutation

PURPOSE

In the past decade, an increasing number of otherwise healthy individuals suffered from invasive fungal infections due to inherited CARD9 mutations. Herein, we present a patient with a homozygous CARD9 mutation who was suffering from localized subcutaneous phaeohyphomycosis caused by the phytopathogenic fungus Pallidocercospora crystallina which has not been reported to cause infections in humans.

METHODS

The medical history of our patient was collected. P. crystallina was isolated from the biopsied tissue. To characterize this novel pathogen, the morphology was analyzed, whole-genome sequencing was performed, and the in vivo immune response was explored in mice. Whole-exome sequencing was carried out with samples from the patient's family. Finally, the expression and function of mutated CARD9 were investigated.

RESULTS

A dark red plaque was on the patient's left cheek for 16 years and was diagnosed as phaeohyphomycosis due to a P. crystallina infection. Whole-genome sequencing suggested that that this strain had a lower pathogenicity. The in vivo immune response in immunocompetent or immunocompromised mice indicated that P. crystallina could be eradicated within a few weeks. Whole-exome sequencing revealed ahomozygous missense mutation in CARD9 (c.1118G>C p.R373P). The mRNA and protein expression levels were similar among cells carrying homozygous (C/C), heterozygous (G/C), and wild-type (G/G) CARD9 alleles. Compared to PBMCs or neutrophils with heterozygous or wild-type CARD9 alleles, however, PBMCs or neutrophils with homozygous CARD9 alleles showed impaired anti-P. crystallina effects.

CONCLUSION

Localized subcutaneous phaeohyphomycosis caused by P. crystallina was reported in a patient with a homozygous CARD9 mutation. Physicians should be aware of the possibility of a CARD9 mutation in seemingly healthy patients with unexplainable phaeohyphomycosis.

MALDI-TOF MS-Based Identification of Melanized Fungi is Faster and Reliable After the Expansion of In-House Database

PURPOSE

Invasive fungal infections caused by melanized fungi are a growing concern. Rapid and reliable identification plays an important role in optimizing therapy. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS)-based identification has emerged as a faster and more accurate diagnostic technique. However, lack of a protein extraction protocol and limited database restricts the identification of melanized fungi by MALDI-TOF MS. The study is designed to standardize protein extraction protocol, to enrich the existing, and to create an in-house database for the rapid identification of melanized fungi.

EXPERIMENTAL DESIGN

In this study, 59 sequence-confirmed, melanized fungi were used to expand and to create an in-house database using a modified protein extraction protocol. A total of 117 clinical isolates are further used to validate the created database.

RESULT

Using existing Bruker database, only 29(24.8%) out of 117 moulds could be identified. However, all the isolates are identified accurately by supplementing the Bruker database with the created in-house database. MALDI-TOF MS takes significantly lesser time for identification compared to DNA sequencing.

CONCLUSION AND CLINICAL RELEVANCE

An expanded database with modified protein extraction protocol can reduce significant time to identify melanized fungi by MALDI-TOF MS.

Nigrograna mackinnonii, Not Trematosphaeria grisea (syn., Madurella grisea), Is the Main Agent of Black Grain Eumycetoma in Latin America

Mycetoma, a chronic and mutilating subcutaneous infection recognized by the WHO as a neglected tropical disease, has been reported in >25 countries in Africa, Asia, and South America. In Latin America, Trematosphaeria grisea is assumed to be the prevalent fungal agent. Recent molecular studies have shown that this is an environmental saprobe in Europe, where it is rarely implicated in human diseases. The aim of the present paper is to establish the identity of Latin American cases ascribed to Trematosphaeria grisea Three cases analyzed were caused by Nigrograna mackinnonii Data on an additional 21 strains in the literature revealed that N. mackinnonii rather than T. grisea is responsible for most cases of black grain eumycetoma in Latin America.

Subcutaneous phaeohyphomycosis in kidney transplant recipients: A series of seven cases

BACKGROUND

Superficial and deep fungal infections are more frequent in transplant recipients primarily because of the failure of cell-mediated immunity and lesser amount of antigen-presenting Langerhans cells in their epidermis. Here, we report seven cases of post-renal transplant subcutaneous phaeohyphomycosis, all of which manifested within 1 year after transplantation and were unresponsive to prolonged courses of itraconazole. This is the first case series, to our knowledge, of phaeohyphomycosis in transplant recipients in India.

METHOD

We performed a retrospective review of cases of phaeohyphomycosis among kidney transplant recipients for type of transplant, immunosuppression, histopathology, and treatment, with prospective follow-up of healed lesion.

RESULTS

An overall incidence of 8.3% was noted, with a median duration of approximately 6 months post transplant to the onset of skin lesion. None of the lesions responded to itraconazole alone and 6/7 lesions were surgically excised. Histopathology showed various lesions and culture could isolate Neocytalidium and Exophiala jeanselmi in two cases.

CONCLUSION

Dematiaceous fungi are increasingly implicated in cutaneous lesions in transplant recipients. Histopathology and surgical excision are the appropriate tools for diagnosis and treatment, respectively.

A Mycoses Study Group International Prospective Study of Phaeohyphomycosis: An Analysis of 99 Proven/Probable Cases

Background

Phaeohyphomycosis is infection caused by dematiaceous, or darkly pigmented, fungi. The spectrum of disease is broad, and optimal therapy remains poorly defined. The Mycoses Study Group established an international case registry of patients with proven/probable phaeohyphomycosis with the goal of improving the recognition and management of these infections.

Methods

Patients from 18 sites in 3 countries were enrolled from 2009-2015. Cases were categorized as local superficial, local deep (pulmonary, sinus, osteoarticular infections), and disseminated infections. End points were clinical response (partial and complete) and all-cause mortality at 30 days and end of follow-up.

Results

Of 99 patients, 32 had local superficial infection, 41 had local deep infection, and 26 had disseminated infection. The most common risk factors were corticosteroids, solid organ transplantation, malignancy, and diabetes. Cultures were positive in 98% of cases. All-cause mortality was 16% at 30 days and 33% at end of follow-up, and 18 of 26 (69%) with dissemination died. Itraconazole was most commonly used for local infections, and voriconazole was used for more severe infections, often in combination with terbinafine or amphotericin B.

Conclusions

Phaeohyphomycosis is an increasingly recognized infection. Culture remains the most frequently used diagnostic method. Triazoles are currently the drugs of choice, often combined with other agents. Further studies are needed to develop optimal therapies for disseminated infections.

First case of Roussoella percutanea bursitis

Roussoella percutanea is a novel opportunistic pathogen firstly identified in 2014. It is known to cause subcutaneous infection in immunosuppressed patients. We report on the first case of R. percutanea bursitis in a renal transplant patient. We provide new data about its identification, drug susceptibility, and treatment outcome. Here we demonstrate that R. percutanea is a potential human pathogen.

Subcutaneous Phaeohyphomycosis Due to Pyrenochaeta romeroi Mimicking a Synovial Cyst

Opportunistic subcutaneous fungal infections are increasing nowadays due to the growing number of medical conditions causing immunosuppression, especially organ transplant. The incidence rate of subcutaneous phaeohyphomycosis is very low. Most studies found are case reports. They showed a wide variation of clinical presentations. Pyrenochaeta romeroi, a fungus from the Dematiaceae group is a saprophyte found in soil and plants and a possible causative agent of phaeohyphomycosis. We present a rare case of subcutaneous phaeohyphomycosis caused by P. romeroi mimicking a synovial cyst in a diabetic patient.

Phaeohyphomycosis in Transplant Patients

Phaeohyphomycosis is caused by a large, heterogenous group of darkly pigmented fungi. The presence of melanin in their cell walls is characteristic, and is likely an important virulence factor. These infections are being increasingly seen in a variety of clinical syndromes in both immunocompromised and normal individuals. Transplant patients are especially at risk due their prolonged immunosuppression. There are no specific diagnostic tests for these fungi, though the Fontana-Masson stain is relatively specific in tissue. They are generally seen in a worldwide distribution, though a few species are only found in specific geographic regions. Management of these infections is not standardized due to lack of clinical trials, though recommendations are available based on clinical experience from case reports and series and animal models. Superficial infections may be treated without systemic therapy. Central nervous system infections are unique in that they often affect otherwise normal individuals, and are difficult to treat. Disseminated infections carry a high mortality despite aggressive therapy, usually with multiple antifungal drugs. Considerable work is needed to determine optimal diagnostic and treatment strategies for these infections.

Phaeohyphomycosis Caused by a Novel Species, Pseudochaetosphaeronema martinelli

Among the opportunistic mycoses that are emerging in patients with immunosuppression or severe underlying illness, many isolates lack of characteristic sporulation and until recently could not be identified. Clinical signs are mostly nonspecific and therefore such infections have often been disregarded. In the present paper we describe a novel, nonsporulating fungal species causing subcutaneous phaeohyphomycosis in two patients of different origin. One is a 73-year-old female from Martinique who suffered from rheumatoid arthritis, while the other case concerns a 72-year-old male from Mexico who had a history of type 2 diabetes mellitus. Sequencing of the partial ribosomal operon revealed that in both cases a member of the order Pleosporales was concerned which could not be affiliated to any family within this order. Multilocus analysis revealed that the fungus was related to another, unaffiliated agent of human mycetoma, Pseudochaetosphaeronema larense, and therefore the name Pseudochaetosphaeronema martinelli was introduced.

Three New Species of the Genus Ochroconis

Ochroconis bacilliformis, O. phaeophora and O. robusta, three novel species of the melanized genus Ochroconis (Sympoventuriaceae, Venturiales), are described, illustrated and distinguished phenotypically and molecularly from previously described species in the genus Ochroconis. Their potential significance for infection of cold-blooded vertebrates is discussed.

Multiple species of Trichosporon produce biofilms highly resistant to triazoles and amphotericin B

Invasive infections caused by Trichosporon spp. have increased considerably in recent years, especially in neutropenic and critically ill patients using catheters and antibiotics. The genus presents limited sensitivity to different antifungal agents, but triazoles are the first choice for treatment. Here, we investigated the biofilm production and antifungal susceptibility to triazoles and amphotericin B of 54 Trichosporon spp. isolates obtained from blood samples (19), urine (20) and superficial mycosis (15). All isolates and 7 reference strains were identified by sequence analysis and phylogenetic inferences of the IGS1 region of the rDNA. Biofilms were grown on 96-well plates and quantitation was performed using crystal violet staining, complemented with Scanning Electron Microscopy (SEM). Susceptibility tests for fluconazole, itraconazole, voriconazole and amphotericin B were processed using the microdilution broth method (CLSI) for planktonic cells and XTT reduction assay for biofilm-forming cells. Our results showed that T. asahii was the most frequent species identified (66.7%), followed by T. faecale (11.1%), T. asteroides (9.3%), T. inkin (7.4%), T. dermatis (3.7%) and one T. coremiiforme (1.8%). We identified 4 genotypes within T. asahii isolates (G1, G3, G4 and G5) and 2 genotypes within T. faecale (G1 and G3). All species exhibited high adhesion and biofilm formation capabilities, mainly T. inkin, T. asteroides and T. faecale. Microscopy images of high biofilm-producing isolates showed that T. asahii presented mainly hyphae and arthroconidia, whereas T. asteroides exhibited mainly short arthroconidia and few filaments. Voriconazole exhibited the best in vitro activity against all species tested. Biofilm-forming cells of isolates and reference strains were highly resistant to all antifungals tested. We concluded that levels of biofilm formation by Trichosporon spp. were similar or even greater than those described for the Candida genus. Biofilm-forming cells were at least 1,000 times more resistant to antifungals than planktonic cells, especially to voriconazole.

Revision of agents of black-grain eumycetoma in the order Pleosporales

Eumycetoma is a chronic fungal infection characterised by large subcutaneous masses and the presence of sinuses discharging coloured grains. The causative agents of black-grain eumycetoma mostly belong to the orders Sordariales and Pleosporales. The aim of the present study was to clarify the phylogeny and taxonomy of pleosporalean agents, viz. Madurella grisea, Medicopsis romeroi (syn.: Pyrenochaeta romeroi), Nigrograna mackinnonii (syn. Pyrenochaeta mackinnonii), Leptosphaeriasenegalensis, L. tompkinsii, and Pseudochaetosphaeronema larense. A phylogenetic analysis based on five loci was performed: the Internal Transcribed Spacer (ITS), large (LSU) and small (SSU) subunit ribosomal RNA, the second largest RNA polymerase subunit (RPB2), and translation elongation factor 1-alpha (TEF1) gene. In addition, the morphological and physiological characteristics were determined. Three species were well-resolved at the family and genus level. Madurella grisea, L. senegalensis, and L. tompkinsii were found to belong to the family Trematospheriaceae and are reclassified as Trematosphaeria grisea comb. nov., Falciformispora senegalensis comb. nov., and F. tompkinsii comb. nov. Medicopsis romeroi and Pseudochaetosphaeronema larense were phylogenetically distant and both names are accepted. The genus Nigrograna is reduced to synonymy of Biatriospora and therefore N. mackinnonii is reclassified as B.mackinnonii comb. Nov. Mycetoma agents in Pleosporales were phylogenetically quite diverse despite their morphological similarity in the formation of pycnidia, except for the ascosporulating genus Falciformispora (formerly in Leptosphaeria). Most of the species diagnosed from human mycetoma were found to be related to waterborne or marine fungi, suggesting an association of the virulence factors with oligotrophism or halotolerance.

Characterization of lignocellulolytic activities from a moderate halophile strain of Aspergillus caesiellus isolated from a sugarcane bagasse fermentation

A moderate halophile and thermotolerant fungal strain was isolated from a sugarcane bagasse fermentation in the presence of 2 M NaCl that was set in the laboratory. This strain was identified by polyphasic criteria as Aspergillus caesiellus. The fungus showed an optimal growth rate in media containing 1 M NaCl at 28°C and could grow in media added with up to 2 M NaCl. This strain was able to grow at 37 and 42°C, with or without NaCl. A. caesiellus H1 produced cellulases, xylanases, manganese peroxidase (MnP) and esterases. No laccase activity was detected in the conditions we tested. The cellulase activity was thermostable, halostable, and no differential expression of cellulases was observed in media with different salt concentrations. However, differential band patterns for cellulase and xylanase activities were detected in zymograms when the fungus was grown in different lignocellulosic substrates such as wheat straw, maize stover, agave fibres, sugarcane bagasse and sawdust. Optimal temperature and pH were similar to other cellulases previously described. These results support the potential of this fungus to degrade lignocellulosic materials and its possible use in biotechnological applications.

Roussoella percutanea, a novel opportunistic pathogen causing subcutaneous mycoses

We report the isolation of a novel agent of subcutaneous mycosis from a 45-year-old Indian male immigrant in the United States. Phylogenetic analysis of partial small ribosomal subunit and large ribosomal subunit, internal transcribed spacer, partial translation elongation factor (TEF1), and RNA polymerase second largest subunit (rPB2) loci revealed that the strain was identical to another isolate previously reported as "Madurella mycetomatis." Both strains clustered in the order Pleosporales, nested in the family Arthopyreniaceae/Roussoellaceae. The fungus differed from known species and hence a new taxon, Roussoella percutanea, is introduced, typified by a strain that showed delayed production of pycnidial conidiomata. Antifungal susceptibility testing suggested that the new species is resistant to echinocandins and flucytosine, with variable results with azoles and amphotericin B.