A rare case of chromoblastomycosis in a renal transplant recipient caused by a non-sporulating species ofRhytidhysteron

Cytology of Rhytidhysteron rufulum: An emerging cause of phaeohyphomycosis

Fine-needle aspiration cytology (FNAC) is often the first-line investigation for detection of any fungal infection. Rhytidhysteron rufulum is an emerging dematiaceous fungus detected as a human pathogen. FNAC combined with molecular techniques helps in the detection of rare fungal species, especially in cases of non-sporulating fungi. We describe the cytomorphologic features of this species in a 62-year immunocompetent male who presented with a localised subcutaneous infection. Molecular studies helped in the final diagnosis.

The origin of human pathogenicity and biological interactions in Chaetothyriales

Fungi in the order Chaetothyriales are renowned for their ability to cause human infections. Nevertheless, they are not regarded as primary pathogens, but rather as opportunists with a natural habitat in the environment. Extremotolerance is a major trend in the order, but quite different from black yeasts in Capnodiales which focus on endurance, an important additional parameter is advancing toxin management. In the ancestral ecology of rock colonization, the association with metabolite-producing lichens is significant. Ant-association, dealing with pheromones and repellents, is another mainstay in the order. The phylogenetically derived family, Herpotrichiellaceae, shows dual ecology in monoaromatic hydrocarbon assimilation and the ability to cause disease in humans and cold-blooded vertebrates. In this study, data on ecology, phylogeny, and genomics were collected and analyzed in order to support this hypothesis on the evolutionary route of the species of Chaetothyriales. Comparing the ribosomal tree with that of enzymes involved in toluene degradation, a significant expansion of cytochromes is observed and the toluene catabolism is found to be complete in some of the Herpotrichiellaceae. This might enhance human systemic infection. However, since most species have to be traumatically inoculated in order to cause disease, their invasive potential is categorized as opportunism. Only in chromoblastomycosis, true pathogenicity might be surmised. The criterion would be the possible escape of agents of vertebrate disease from the host, enabling dispersal of adapted genotypes to subsequent generations.

Molecular epidemiology of clinical filamentous fungi in Qatar beyond Aspergillus and Fusarium with notes on the rare species

Due to an increasing number of patients at risk (i.e., those with a highly compromised immune system and/or receiving aggressive chemotherapy treatment), invasive fungal infections (IFI) are increasingly being reported and associated with high mortality rates. Aspergillus spp., particularly A. fumigatus, is the major cause of IFI caused by filamentous fungi around the world followed by Fusarium spp., however, other fungi are emerging as human pathogens. The aim of this study was to explore the epidemiology and prevalence of the non-Aspergillus and non-Fusarium filamentous fungi in human clinical samples over an 11-year period in Qatar using molecular techniques. We recovered 53 filamentous fungal isolates from patients with various clinical conditions. Most patients were males (75.5%), 9.4% were immunocompromised, 20.7% had IFI, and 11.3% died within 30 days of diagnosis. The fungal isolates were recovered from a variety of clinical samples, including the nasal cavity, wounds, respiratory samples, body fluids, eye, ear, tissue, abscess, and blood specimens. Among the fungi isolated, 49% were dematiaceous fungi, followed by Mucorales (30%), with the latter group Mucorales being the major cause of IFI (5/11, 45.5%). The current study highlights the epidemiology and spectrum of filamentous fungal genera, other than Aspergillus and Fusarium, recovered from human clinical samples in Qatar, excluding superficial infections, which can aid in the surveillance of uncommon and emerging mycoses.

Implantation subcutaneous phaeohyphomycosis caused by Rhytidhysteron rufulum: A case report

Subcutaneous phaeohyphomycosis is caused by traumatic implantation of melanized environmental fungi. The majority of cases occur in tropical areas of the world or are associated with travel from these regions. Herein, we describe a rare case of subcutaneous phaeohyphomycosis caused by Rhytidhysteron rufulum in an immunocompetent Somalia-born patient. The use of molecular diagnostics as an essential tool for identification of rare fungal pathogens is highlighted.

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.

Reviewing the Etiologic Agents, Microbe-Host Relationship, Immune Response, Diagnosis, and Treatment in Chromoblastomycosis

Chromoblastomycosis (CBM) is a neglected human disease, caused by different species of pigmented dematiaceous fungi that cause subcutaneous infections. This disease has been considered an occupational disease, occurring among people working in the field of agriculture, particularly in low-income countries. In 1914, the first case of CBM was described in Brazil, and although efforts have been made, few scientific and technological advances have been made in this area. In the field of fungi and host cell relationship, a very reduced number of antigens were characterized, but available data suggest that ectoantigens bind to the cell membrane of host cells and modulate the phagocytic, immunological, and microbicidal responses of immune cells. Furthermore, antigens cleave extracellular proteins in tissues, allowing fungi to spread. On the contrary, if phagocytic cells are able to present antigens in MHC molecules to T lymphocytes in the presence of costimulation and IL-12, a Th1 immune response will develop and a relative control of the disease will be observed. Despite knowledge of the resistance and susceptibility in CBM, up to now, no effective vaccines have been developed. In the field of chemotherapy, most patients are treated with conventional antifungal drugs, such as itraconazole and terbinafine, but these drugs exhibit limitations, considering that not all patients heal cutaneous lesions. Few advances in treatment have been made so far, but one of the most promising ones is based on the use of immunomodulators, such as imiquimod. Data about a standard treatment are missing in the medical literature; part of it is caused by the existence of a diversity of etiologic agents and clinical forms. The present review summarizes the advances made in the field of CBM related to the diversity of pathogenic species, fungi and host cell relationship, antigens, innate and acquired immunity, clinical forms of CBM, chemotherapy, and diagnosis.

Three new species of Rhytidhysteron (Dothideomycetes, Ascomycota) from Mexico

The genus Rhytidhysteron is characterised by forming navicular to apothecial hysterothecia, exposing the green, yellow, orange, red, vinaceous or black colours of the hymenium which generally releases pigments in the presence of KOH. The exciple is smooth or striated, the asci bitunicate and ascospores have 1–5 transverse septa. To date, twenty-six Rhytidhysteron species have been described from the Tropics. The present study aims to describe three new species in the Neotropics of Mexico based on molecular methods and morphological features. Illustrations and a taxonomic key are provided for all known species of this genus. Rhytidhysteroncozumelense from the Isla Cozumel Biosphere Reserve, R.esperanzae from the Sierra Juárez, Oaxaca and R.mesophilum from the Sierra Madre Oriental, Hidalgo are described as new species. With the present study, the number of species of Rhytidhysteron known from Mexico is now increased to eight.

Emerging mould infections: Get prepared to meet unexpected fungi in your patient

Invasive fungal diseases are increasing issues in modern medicine, where the human immunodeficiency virus (HIV) pandemic and the wider use of immunosuppressive drugs generate an ever-growing number of immunocompromised patients with an increased susceptibility to uncommon fungal pathogens. In the past decade, new species have been reported as being responsible for disseminated and invasive fungal diseases in humans. Among them, the following genera are rare but seem emerging issues: Scopulariopsis, Hormographiella, Emergomyces, Westerdykella, Trametes, Actinomucor, Saksenaea, Apophysomyces, and Rhytidhysteron. Delay in diagnosis, which is often the case in these infections, jeopardizes patients' prognosis and leads to increased mortality. Here we summarize the clinical and biological presentation and the key features to identify these emerging pathogens and we discuss the available antifungal classes to treat them. We focused on Pubmed to recover extensively reported human invasive cases and articles regarding the nine previously cited fungal organisms. Information concerning patient background, macroscopic and microscopic description and pictures of these fungal organisms, histological features in tissues, findings with commonly used antigen tests in practice, and hints on potential efficient antifungal classes were gathered. This review's purpose is to help clinical microbiologists and physicians to suspect, identify, diagnose, and treat newly encountered fungi in hospital settings.

Subcutaneous Fungal Infection Caused by a Non-sporulating Strain of Corynespora cassiicola Successfully Treated with Terbinafine

Corynespora cassiicola is a common plant pathogen, but C. cassiicola infection in human hosts is extremely rare. In this report, we present an 84-year-old male with long-term use of inhaled corticosteroids who developed a subcutaneous infection caused by C. cassiicola. The organism was isolated from both wound culture and biopsy specimen from the skin lesion. However, no microscopic diagnostic characters could be obtained because the isolates failed to sporulate on different culture media. Molecular diagnosis by amplification and sequencing of the internal transcribed spacer regions of ribosomal DNA was performed, and the sequences of the isolates were identical to those of C. cassiicola. The patient was treated successfully with oral terbinafine therapy for 12 weeks. In this report, we also review the epidemiology, clinical and therapeutic facets of cutaneous C. cassiicola infection.

Two new species of Gloniopsis (Hysteriales, Ascomycota) from clinical specimens: Morphological and molecular characterisation

BACKGROUND

The coelomycetes comprise a wide range of fungal species distributed in at least three different classes of the phylum Ascomycota. These are morphologically characterised by producing their conidia inside of fruiting bodies called pycnidia or acervuli, and only a reduced number of species are able to cause human infections. However, their identification in the clinical laboratory is often difficult, due to their few morphological features or because they remain sterile.

MATERIALS AND METHODS

In the present study, three isolates of coelomycetes of clinical origin were phenotypically and molecularly studied, by sequencing the D1-D2 fragment of the 28S nuclear ribosomal RNA (nrRNA) (LSU), the internal transcribed spacer region (ITS1-5.8S-ITS2) and a fragment of the translation elongation factor 1-alpha (tef1) genes.

RESULTS AND CONCLUSIONS

As result of the molecular analysis, the isolates were identified as belonging to the genus Gloniopsis (order Hysteriales, Dothideomycetes) but without the characteristics of any of the species described so far. Therefore, we propose the new species Gloniopsis percutanea and Gloniopsis pneumoniae. Furthermore, this study revealed that some isolates from clinical specimens identified previously as Rhytidhysteron spp. were misidentified, and considering the few studies in the order Hysteriales and the scarce number of sequences of phylogenetic markers, future revisions of this order should be performed to clarify their taxonomy and obtain a better identification from isolates involved in human mycoses.

Subcutaneous Rhytidhysteron Infection: A Case Report from South India with Literature Review

Rhytidhysteron is a saprophytic dematiaceous fungus which rarely infects humans. Though virtually all individuals are exposed, very few develop the disease. Only seven human cases are reported till date. The present case is the second case from South India.

A 40-year-old immunocompetent female agricultural worker, presented with a swelling on the dorsum of the right hand. Fine needle aspiration cytology (FNAC) of the swelling revealed short, thick, branched septate fungal hyphae. The isolate was moderately slow growing; grayish white colonies were observed on Sabouraud’s Dextrose Agar (SDA) slant. On further incubation, the colonies turned floccose, greyish black and the black pigment was observed on the reverse. Microscopy of lactophenol cotton blue tease mount showed thick, brown septate hyphae without any fruiting bodies. Molecular typing confirmed the isolates as Rhytidhysteron rufulum.

Identification of all clinical isolates of nonsporulating fungi to genus level is necessary to identify rare fungi infecting humans.

Chromoblastomycosis in India: Review of 169 cases

Chromoblastomycosis (CBM) is a chronic, progressive, cutaneous and subcutaneous fungal infection following the traumatic implantation of certain dematiaceous fungi. The disease has worldwide prevalence with predominant cases reported from humid tropical and subtropical regions of America, Asia, and Africa. Diagnosis is often delayed or misdirected either due to poor degree of clinical suspicions or clinical simulation of dermatological conditions. The infection is not uncommon in India and several case reports from the sub-Himalayan belt and western and eastern coasts of India have been published; however, very few have reviewed the cases. We reviewed 169 cases published in English literature from India during 1957 through May 2016, including 2 recent cases from our institute. A tremendous increase in the number of reported cases was noticed since 2012, since which, more than 50% of the cases had been published. A majority of the patients (74.1%) were involved in various agricultural activities directly or indirectly. The mean age at presentation was 43.3 years ± 16.0, with male to female ratio of 4.2:1. The duration of disease at the time of presentation varied from 20 days to 35 years. Any history of trauma was recalled only in 33.8% of the studied cases. The lower extremity was the most common site afflicted, followed by the upper extremity. The culture was positive in 80.3% of the cases with Fonsecaea pedrosoi, isolated as the most common fungal pathogen, followed by Cladophialophora carrionii. Although all the commercially available antifungals were prescribed in these cases, itraconazole and terbinafine were the most commonly used, either alone or in combination with other drugs/physical methods, with variable degrees of outcome. Combinations of different treatment modalities (chemotherapy and physical methods) yielded a cure rate of 86.3%. CBM is refractory to treatment and no single antifungal agent or regimen has demonstrated satisfactory results. Increased awareness with early clinical suspicion of the disease and adequate therapy are necessary to improve the outcome. However, depending upon the causative agent, disease severity, and the choice of antifungals, variable outcomes can be observed.

Melanized fungal infections in kidney transplant recipients: contributions to optimize clinical management

OBJECTIVES

This is a retrospective and observational study addressing clinical and therapeutic aspects of melanized fungal infections in kidney transplant recipients.

METHODS

We retrospectively reviewed medical records of all patients admitted between January 1996 and December 2013 in a single institution who developed infections by melanized fungi.

RESULTS

We reported on 56 patients aged between 30 and 74 years with phaeohyphomycosis or chromoblastomycosis (0.54 cases per 100 kidney transplants). The median time to diagnosis post-transplant was 31.2 months. Thirty-four (60.8%) infections were reported in deceased donor recipients. Fifty-one cases of phaeohyphomycosis were restricted to subcutaneous tissues, followed by two cases with pneumonia and one with brain involvement. Most dermatological lesions were represented by cysts (23/51; 45.1%) or nodules (9/51; 17.9%). Exophiala spp. (34.2%) followed by Alternaria spp. (7.9%) were the most frequent pathogens. Graft loss and death occurred in two patients and one patient, respectively. Regarding episodes of subcutaneous phaeohyphomycosis, a complete surgical excision without antifungal therapy was possible in 21 of 51 (41.2%) patients. Long periods of itraconazole were required to treat the other 30 (58.8%) episodes of subcutaneous disease. All four cases of chromoblastomycosis were treated only with antifungal therapy.

CONCLUSIONS

Melanized fungal infections should be considered in the differential diagnosis of all chronic skin lesions in transplant recipients. It is suggested that the impact of these infections on graft function and mortality is low. The reduction in immunosuppression should be limited to severely ill patients.

Spectral Manifestation of Melanized Fungal Infections in Kidney Transplant Recipients: Report of Six Cases

Chromoblastomycosis and phaeohyphomycosis are melanized fungal infections, which affect skin and subcutaneous tissues in immunocompetent and immunosuppressed patients, as solid-organ transplant recipients, respectively. In this present study, we report six cases of melanized fungal infection in kidney transplant recipients. In five cases, culture of tissue specimens identified two cases of Exophiala spp. and three cases of Fonsecaea spp. Molecular identification was performed in three cases based on sequencing of rDNA (ITS region) that revealed the following agents: Exophiala xenobiotica, Exophiala bergeri and Fonsecaea monophora. Clinically, they presented verrucous lesion, erythematous-squamous plaque, nodules and lymphangitic distribution. Histopathological aspect was tuberculous granuloma, with concomitant presence of muriform bodies and hyphae. Some patients presented fungal transepithelial elimination. One patient received only terbinafine. Three patients underwent surgery, and two of them received itraconazole. In these four cases, the infection did not relapse. The other two patients were treated only with itraconazole, one of them is still under treatment and the other one was lost to follow-up. These patients presented clinical and histopathological characteristics ranging from resistant to nonresistant forms.

Chromoblastomycosis

Chromoblastomycosis is a chronic fungal infection of the skin and subcutaneous tissue. The infection usually results from a traumatic injury and inoculation of microorganism from a specific group of dematiaceous fungi (usually Fonsecaea pedrosoi, Phialophora verrucosa, Cladophialophora carrionii). In the tissues fungi produce characteristic sclerotic cells or muriform cells. Dermal lesions can range from small nodules to large papillary-like eruptions. The disease has been described worldwide but the prevalence is higher in rural populations in countries with a tropical or subtropical climate, such as Madagascar in Africa and Brazil in South America. Diagnostic techniques are based on direct examination, culture and histopathology. Despite a variety of treatment modalities, which include long courses of antifungals, surgical excision and destructive physical therapies, the disease remains one of the most difficult deep mycotic infections to eradicate.

Subcutaneous mycoses caused by Rhytidhysteron species in an immunocompetent patient

Subcutaneous mycoses are chronic fungal infections of the skin and subcutaneous tissues caused by variety of fungal agents and usually occur following trauma with vegetative matter. We report a case of subcutaneous mycoses caused by rare fungus belonging to the genus Rhytidhysteron, in an immunocompetent male who presented with a subcutaneous nodule on left foot. This unusual species was identified and confirmed by molecular methods.

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

Subcutaneous infections caused by melanised fungi have been increasingly reported among transplant patients, and these infections have the potential for blood and visceral dissemination. Some moulds, such as Mycelia sterilia, cannot grow and sporulate on different media, making their identification impossible by conventional methods. The fast and accurate identification of melanised fungi at the species level is important because species may have tropism to different organs and different susceptibilities to antifungal agents. Molecular tools have been reported to be helpful for the species identification of non-sporulating moulds. Our goal was to identify the species of M. sterilia isolates obtained from clinical samples of transplant patients using sequences of ITS and the D1/D2 regions of rDNA. Clinical samples were obtained from eight kidney transplant recipients who developed subcutaneous fungal infections. The diagnosis was confirmed by histopathology and conventional culture. Histopathology showed septated, melanised hyphae, and the cultures identified non-sporulating fungi. Therefore, the DNA from the M. sterilia isolates was subjected to PCR amplification and sequencing of the ITS and D1/D2 regions. Genus/species identification was obtained by comparison with gene banks. We obtained the following identifications: Alternaria sp. (2), Cochliobolus lunatus/Curvularia lunata (2), Cochliobolus hawaiiensis/Bipolaris hawaiiensis (1), Ochroconis sp. (1), Medicocopsis romeroi/Pyrenochaeta romeroi (1) and Nigrograna mackinnonii/Pyrenochaeta mackinnonii (1).