In Vitro Susceptibility Profiles of Eight Antifungal Drugs against Clinical and Environmental Strains of Phaeoacremonium

An updated list of eumycetoma causative agents and their differences in grain formation and treatment response

SUMMARYIn 2023, the World Health Organization designated eumycetoma causative agents as high-priority pathogens on its list of fungal priority pathogens. Despite this recognition, a comprehensive understanding of these causative agents is lacking, and potential variations in clinical manifestations or therapeutic responses remain unclear. In this review, 12,379 eumycetoma cases were reviewed. In total, 69 different fungal species were identified as causative agents. However, some were only identified once, and there was no supporting evidence that they were indeed present in the grain. Madurella mycetomatis was by far the most commonly reported fungal causative agent. In most studies, identification of the fungus at the species level was based on culture or histology, which was prone to misidentifications. The newly used molecular identification tools identified new causative agents. Clinically, no differences were reported in the appearance of the lesion, but variations in mycetoma grain formation and antifungal susceptibility were observed. Although attempts were made to explore the differences in clinical outcomes based on antifungal susceptibility, the lack of large clinical trials and the inclusion of surgery as standard treatment posed challenges in drawing definitive conclusions. Limited case series suggested that eumycetoma cases caused by Fusarium species were less responsive to treatment than those caused by Madurella mycetomatis. However, further research is imperative for a comprehensive understanding.

Fungal Whole-Genome Sequencing for Species Identification: From Test Development to Clinical Utilization

Using next-generation sequencing (NGS), we developed and validated a whole-genome sequencing (WGS)-based clinical test for fungal species identification on clinical isolates. The identification is mainly based on the fungal ribosomal internal transcribed spacer (ITS) region as the primary marker, and additional marker and genomic analysis applied for species within the Mucorales family (using the 28S rRNA gene) and Aspergillus genus (using the beta-tubulin gene and k-mer tree-based phylogenetic clustering). The validation study involving 74 unique fungal isolates (22 yeasts, 51 molds, and 1 mushroom-forming fungus) showed high accuracy, with 100% (74/74) concordance on the genus-level identifications and 89.2% (66/74) concordance on the species level. The 8 discrepant results were due to either the limitation of conventional morphology-based methodology or taxonomic changes. After one year of implementation in our clinical laboratory, this fungal NGS test was utilized in 29 cases; the majority of them were transplant and cancer patients. We demonstrated the utility of this test by detailing five case studies, in which accurate fungal species identification led to correct diagnosis, treatment adjustment or was ruled out for hospital acquired infection. This study provides a model for validation and implementation of WGS for fungal identification in a complex health system that serves a large immunocompromised patient population.

Fungal Osteomyelitis due to Phaeoacremonium venezuelense: A Case Report

CASE

A 56-year-old immunosuppressed man presented with pain and swelling in the medial and anterior right foot with accompanied numbness in the second and third toes 1 month after a puncture wound by a Sylvester palm tree thorn. An intraoperative culture/biopsy returned positive for septic arthritis of the naviculocuneiform joint and fungal osteomyelitis of the navicular, medial, and intermediate cuneiforms due to Phaeoacremonium venezuelense.

CONCLUSION

Fungal osteomyelitis is extremely rare. Only 5 cases by Phaeoacremonium venezuelense have been reported previously in the literature. To the best of our knowledge, this is the first case of osteomyelitis by this strain.

A rare case of phaeohyphomycosis due to Phaeoacremonium krajdenii from Odisha

A 45-year-old healthy woodcutter presented with a cystic swelling on the sole of the left great toe. Other than barefoot walking, there was no history of trauma or significant illness in the past. Fine needle aspirate showed yeast and hyphae on microscopy and culture grew black mould which was identified as Phaeoacremonium krajdenii species and genus confirmed by internal transcribed spacer sequencing. Aspiration of the lesion resulted in cure. Phaeoacremonium is a genus of fungi which are rare human pathogens, and herein we report a rare case of phaeohyphomycosis due to Phaeoacremonium krajdenii from the state of Odisha, India.

First report of a new corneal pathogen: Phaeoacremonium parasiticum

Keratitis is a public health issue in developing countries and a potentially sight-threatening condition. Collagen fibrils in the corneal stroma are parallels to each other. Fundamental substance maintains the same space between collagen fibrils. That is how corneal transparency can be achieved. Any damage which can modify this structure will lead to corneal opacity and loss of vision. Fungal keratitis might appear in up to one-third of cases. Nevertheless, fungal keratitis remains poorly described and understood. Herein, we present the first ever reported case of corneal infection due to Phaeoacremonium parasiticum in a young patient. We describe the clinical and microbial characteristics, and we also discuss the use of confocal microscopy in early diagnosis of this infection.

Phaeoacremonium species detected in fine needle aspiration: a rare case report

Background

Fine needle aspiration cytology (FNAC) with rapid on-site evaluation has a great potential for the diagnosis of fungal lesions and other opportunistic infections. Fungal infections have been in increasing trend in the past two decades due to immunosuppression, travel, and environmental exposure. Human disease caused by Phaeoacremonium species is rare and was first reported in 1974 as subcutaneous tissue infection in a renal transplant recipient.

Case presentation

We report a case of subcutaneous tissue swelling in a 67-year-old male, wherein FNAC was done with incidental detection of the fungus (Phaeoacremonium spp).

Conclusion

There are very few reported cases of subcutaneous infection in humans by Phaeoacremonium spp. Clinical suspicion and FNAC can play an important role in early detection of the fungus, prevent spread, and facilitating early treatment.

The type isolate of a rare Phaeoacremonium species as a cause of human eumycetoma

An isolate of unknown identity that had been identified as causing eumycetoma was retained in an international culture collection, and eventually became the nomenclatural type isolate of the rarely encountered Phaeoacremonium sphinctrophorum. The case featured an indurated, painless, swollen lesion on the dorsum of the foot that had developed in a Canadian resident who had previously been a farmer in Laos. Resection alone was curative.

Isavuconazole for treatment of rare invasive fungal diseases

Data regarding treatment of rare invasive fungal diseases (IFDs) are scarce. We documented the efficacy and safety of isavuconazole for treatment of uncommonly diagnosed IFDs. VITAL was a single-arm, international, open-label study evaluating the efficacy and safety of isavuconazole (200 mg orally or intravenously every 8 hours for 48 hours, then once daily). The primary outcome was overall response at Day 42; key secondary outcomes were overall responses at Day 84 and end of treatment (EOT), mortality at Days 42 and 84, and safety. This analysis includes patients with IFD caused by rare or unidentified pathogens. Twenty-six patients with IFDs caused by rare moulds (n = 17), non-Candida yeasts (n = 2), or unidentified moulds (n = 7) were enrolled (median treatment duration [range], 114.5 [1-496]) days. Overall treatment success was observed in 11/26 (42.3%), 10/26 (38.5%), and 15/26 (57.7%) patients at Days 42, 84, and EOT, respectively. All-cause mortality rates were 2/26 patients (7.7%) at Day 42 and 4/26 patients (15.4%) at Day 84; another two patients died after Day 84. All patients had ≥1 treatment-emergent adverse event (TEAE); 15 patients (57.7%) had serious TEAEs, and TEAEs led to discontinuation of isavuconazole in four patients (15.4%). Isavuconazole may be efficacious for treatment of a range of rare IFDs.