DNA sequencing to clarify the taxonomical conundrum of the clinical coelomycetes

First Report of Neocucurbitaria unguis-hominis Keratitis

Coelomycetous fungi are among the emerging causes of infections and have been involved in many kinds of infections, including keratitis and endophtalmitis. Here, we present the first case of keratitis caused by Neocucurbitaria unguis-hominis, a coelomycetous fungus belonging to the family Cucurbitariaceae. In this case report, we describe the clinical presentation of a 56-year-old woman, a regular contact lens wearer, who was treated for pain in her right eye and fixed spot vision after an injury with plant debris. On examination, a corneal ulcer was observed, the foreign body was removed, and topical eye-drop therapy was started. After an initial improvement, the patient returned three weeks later due to a recurrence of discomfort in her right eye, observing the persistence of the corneal ulcer. Corneal scrapings were taken for culture, growing a filamentous fungus after seven days, which was identified by sequencing the fungal internal transcribed spacer region. It should be noted that microbiological identification of the coelomycetes in the clinical laboratory is not easy because of their difficulty in sporulating, making molecular techniques based on the amplification and sequencing of appropriate phylogenetic markers essential. Identification of these fungi is mandatory in order to optimise treatment due to the difficulty in eradicating them with antifungal treatment, requiring surgery in 50% of cases.

Meanderella rijsii, a new opportunist in the fungal order Pleosporales

Subcutaneous phaeohyphomycosis is an implantation disease caused by melanized fungi and affect both immunocompetent as well as immunocompromised individuals. Diagnosis and treatment require proper isolation and accurate identification of the causative pathogen. We isolated a novel fungus from a case of subcutaneous phaeohyphomycosis in an immunocompetent patient. The 56-year-old patient suffered from a slowly progressive swelling on the metatarsophalangeal join of the left food. The isolated fungus lacked sporulation and sequences of the ribosomal operon did not match with any known species. In a multi-locus phylogenetic analysis involving five markers, the fungus formed a unique lineage in the order Pleosporales, family Trematosphaeriaceae. A new genus, Meanderella and a new species, M. rijsii are here proposed to accommodate the clinical isolate. Whole genome analysis of M. rijsii revealed a number of genes that can be linked to pathogenicity and virulence. Further studies are however needed to understand the role of each gene in the pathogenic process and to determine the origin of pathogenicity in the family of Trematosphaeriaceae.

A new pleosporalean fungus isolated from superficial to deep human clinical specimens

Human infections by pleosporalean fungi (class Dothideomycetes, phylum Ascomycota) are rarely reported. Because their identification is challenging using morphological characterization, several phylogenetic markers must be sequenced for an accurate identification and taxonomical placement of the isolates. Three isolates of clinical origin were phenotypically characterized, but due to the absence of relevant morphological traits, D1-D2 domains of the 28S nrRNA gene (LSU), the internal transcribed spacer region (ITS) of the nrRNA, and fragments of the RNA polymerase II subunit 2 (rpb2) and translation elongation factor 1-alpha (tef1) genes were sequenced to allow a phylogenetic analysis that would solve their phylogenetic placement. That analysis revealed that these isolates did not match any previously known pleosporalean genera, and they are proposed here as the new fungal genus, Gambiomyces. Unfortunately, the isolates remained sterile, which, consequently, made the morphological description of the reproductive structures impossible. Future studies should try to understand the behaviour of this fungus in nature as well as its characteristics as an opportunistic fungal pathogen. Molecular identification is becoming an essential tool for proper identification of Dothideomycetes of clinical origin.

LAY ABSTRACT

We describe a new pleosporalen pathogenic fungus, Gambiomyces profunda, found in superficial to deep samples from a human patient. Because all strains remained sterile, the fungus was finally identified following a phylogenetic analysis by using four different molecular markers.

Neocucurbitaria keratinophila: An emerging opportunistic fungus causing superficial mycosis in Spain

Although there have been few reports of opportunistic infections (superficial and systemic) caused by coelomycetous fungi, they are becoming more frequent. Neocucurbitaria keratinophila (formerly Pyrenochaeta keratinophila), characterized by producing pycnidial conidiomata and small hyaline conidia, seems to be an emergent opportunistic pathogen in Spain. Since this fungus was first reported from human keratitis, eight strains have been isolates from clinical cases in Spain. This is a retrospective study of these fungal strains, including phenotypic and molecular characterizations, and in vitro antifungal susceptibility assays. These clinical strains were identified by sequencing four phylogenetic markers such as the internal transcribed spacer region (ITS1-5.8S-ITS2) and fragments of the 28S nrRNA (LSU), beta-tubulin (tub2), and RNA polymerase II subunit 2 (rpb2) genes, and by morphological characterization. All the strains tested were susceptible to the majority of antifungals, being isavuconazole the only drug that showed a poor antifungal activity.

Deep cutaneous fungal infections in solid-organ transplant recipients

BACKGROUND

Deep cutaneous fungal infections (DCFIs) are varied in immunosuppressed patients, with few data for such infections in solid-organ transplant recipients (s-OTRs).

OBJECTIVE

To determine DCFI diagnostic characteristics and outcome with treatments in s-OTRs.

METHODS

A 20-year retrospective observational study in France was conducted in 8 primary dermatology-dedicated centers for s-OTRs diagnosed with DCFIs. Relevant clinical data on transplants, fungal species, treatments, and outcomes were analyzed.

RESULTS

Overall, 46 s-OTRs developed DCFIs (median delay, 13 months after transplant) with predominant phaeohyphomycoses (46%). Distribution of nodular lesions on limbs and granulomatous findings on histopathology were helpful diagnostic clues. Treatments received were systemic antifungal therapies (48%), systemic antifungal therapies combined with surgery (28%), surgery alone (15%), and modulation of immunosuppression (61%), leading to complete response in 63% of s-OTRs.

LIMITATIONS

Due to the retrospective observational design of the study.

CONCLUSIONS

Phaeohyphomycoses are the most common DCFIs in s-OTRs. Multidisciplinary teams are helpful for optimal diagnosis and management.

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.