In vitro activities of antifungal drugs against environmentalExophialaisolates and review of the literature

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.

Influence of Green Human Resource Management on firm's environmental performance: Green Employee Empowerment as a mediating factor

This research aimed to investigate the mediating function of Green Employee Empowerment (GEE) in the relationship between Green Human Resource Management practices (GHRM) and the environmental performance of small and medium-sized enterprises (SMEs) in Ghana, drawing on the Ability-Motivation-Opportunity (AMO) theory. This study assessed the hypotheses in the established research model using structural equation modeling based on data collected from 320 participants from small and medium-sized firms in Ghana. The study's results revealed that GHRM practices were significantly correlated with the firm's environmental performance. The study found significant GHRM's indirect consequences on environmental performance through GEE in all models examined. These findings suggest that GEE plays a crucial role in translating the impact of GHRM practices into improved environmental performance. The study overlooked other potential mediators or moderators in the relationship between GHRM practices and environmental performance, focusing on GEE. To better understand the complex dynamics behind GHRM techniques' environmental performance, future research might examine business culture, leadership style, and employee sustainability attitudes.

Topical 1% Voriconazole for Mixed Scedosporium and Exophiala Subcutaneous Infection in a Kidney Transplant Recipient

Abstract is missing (Short communication)

Terbinafine prevents colorectal cancer growth by inducing dNTP starvation and reducing immune suppression

Existing evidence indicates that gut fungal dysbiosis might play a key role in the pathogenesis of colorectal cancer (CRC). We sought to explore whether reversing the fungal dysbiosis by terbinafine, an approved antifungal drug, might inhibit the development of CRC. A population-based study from Sweden identified a total of 185 patients who received terbinafine after their CRC diagnosis and found that they had a decreased risk of death (hazard ratio = 0.50) and metastasis (hazard ratio = 0.44) compared with patients without terbinafine administration. In multiple mouse models of CRC, administration of terbinafine decreased the fungal load, the fungus-induced myeloid-derived suppressor cell (MDSC) expansion, and the tumor burden. Fecal microbiota transplantation from mice without terbinafine treatment reversed MDSC infiltration and partially restored tumor proliferation. Mechanistically, terbinafine directly impaired tumor cell proliferation by reducing the ratio of nicotinamide adenine dinucleotide phosphate (NADP+) to reduced form of nicotinamide adenine dinucleotide phosphate (NADPH), suppressing the activity of glucose-6-phosphate dehydrogenase (G6PD), resulting in nucleotide synthesis disruption, deoxyribonucleotide (dNTP) starvation, and cell-cycle arrest. Collectively, terbinafine can inhibit CRC by reversing fungal dysbiosis, suppressing tumor cell proliferation, inhibiting fungus-induced MDSC infiltration, and restoring antitumor immune response.

A fatal neonatal case of fungemia due to Exophiala dermatitidis-case report and literature review

Background

Systemic infections caused by the black yeast-like fungus Exophiala dermatitidis are rare, but are associated with high mortality especially in immunocompromised patients. We report the first case of E. dermatitidis fungemia in a premature extremely low birth weight (ELBW) neonate who succumbed despite antifungal therapy with liposomal amphotericin (AMB) and fluconazole. A systematic review of all fungemia cases due to E. dermatitidis was also conducted aiming for a better understanding of the risk factors, treatment strategies and outcomes.

Case presentation

A male, ELBW premature neonate, soon after his birth, developed bradycardia, apnoea and ultimately necrotizing enterocolitis with intestinal perforation requiring surgical intervention. Meanwhile, he had also multiple risk factors for developing bloodstream infection, such as intubation, mechanical ventilation, central venous catheter (CVC), parenteral nutrition, empirical and prolonged antibiotic use. His blood cultures were positive, firstly for Acinetobacter junii and then for Klebsiella pneumoniae together with E. dermatitidis while on fluconazole prophylaxis and antibiotic empiric therapy. Despite the treatment with broad spectrum antibiotics, liposomal AMB and fluconazole, the newborn succumbed. A literature review identified another 12 E. dermatitidis bloodstream infections, mainly in patients with hematologic malignancies and solid organ transplant recipients (61%), with overall mortality 38% despite CVC removal and antifungal therapy.

Conclusions

Due to the rarity of E. dermatitidis infections, little is known about the characteristics of this yeast, the identification methods and the optimal therapy. Identification by common biochemical tests was problematic requiring molecular identification. Resolution of neonatal fungemia is difficult despite proper antifungal therapy especially in cases with multiple and severe risk factors like the present one. Therapeutic intervention may include CVC removal and treatment for at least 3 weeks with an azole (itraconazole or fluconazole after susceptibility testing) or AMB monotherapy but not echinocandins or AMB plus azole combination therapy.

In vitro activities of 8 antifungal drugs against 126 clinical and environmental Exophiala isolates

BACKGROUND

Exophiala is the main genus of black fungi comprising numerous opportunistic species. Data on antifungal susceptibility of Exophiala isolates are limited, while infections are potentially fatal.

MATERIALS AND METHODS

In vitro activities of eight antifungal drugs (AMB, five azoles, two echinocandins) against 126 clinical (n = 76) and environmental (n = 47) isolates from around the world were investigated. E. oligosperma (n = 58), E. spinifera (n = 33), E. jeanselmei (n = 14) and E. xenobiotica (n = 21) were included in our dataset.

RESULTS

The resulting MIC₉₀ s of all strains were as follows, in increasing order: posaconazole 0.063 μg/ml, itraconazole 0.125 μg/ml, voriconazole and amphotericin B 1 μg/ml, isavuconazole 2 μg/ml, micafungin and caspofungin 4 μg/ml, and fluconazole 64 μg/ml. Posaconazole, itraconazole and micafungin were the drugs with the best overall activity against Exophiala species. Fluconazole could not be considered as a treatment choice. No significant difference could be found among antifungal drug activities between these four species, neither in clinical nor in environmental isolates.

CONCLUSION

Antifungal susceptibility data for Exophiala spp. are crucial to improve the management of this occasionally fatal infection and the outcome of its treatment.

In vitro susceptibility testing for black grain eumycetoma causative agents

Eumycetoma is a neglected tropical implantation mycosis characterized by large subcutaneous swellings. Inside the infected tissue, the causative agents are found in grains. The most common causative agents form black grains and are sterile upon isolation. In vitro susceptibility assays were developed for eumycetoma causative agents. They were based on the Clinical and Laboratory Standards Institute M38A protocol and modified to enable the use of hyphae as a starting inoculum. To ease endpoint reading, viability dyes such as resazurin or XTT have been used. So far the in vitro susceptibility assays developed have mainly been used to establish if causative agents are inhibited in growth by various antifungal agents, but not for clinical decision making. For drug discovery, the assay proved useful in determining which compounds were able to prevent hyphal growth. However, a clear correlation between in vitro inhibition in terms of the half maximal inhibitory concentration or 50% minimum inhibitory concentration (MIC50) and therapeutic efficacy assayed in a novel model system in terms of Galleria mellonella larval survival was not found. For clinical decision making, a range of MICs were found for each antifungal agent. However, no clinical breakpoints have been established for any of the causative agents. For itraconazole, the MIC50 of most causative agents was below the attainable serum levels, which might indicate that they are susceptible. However, before in vitro susceptibility can be used in clinical decision making for mycetoma, a correlation between MIC and clinical outcome needs to be made.

Doubly Misdiagnosed: Exophiala Masquerading as Squamous Cell Carcinoma and Chromoblastomycosis

ABSTRACT

Deep cutaneous fungal infections (DCFI) can arise in the setting of skin trauma and immunosuppression. DCFI may be secondary to chromoblastomycosis, which is typically characterized by pseudoepitheliomatous hyperplasia histologically and can be mistaken for squamous cell carcinoma. In addition, "copper penny" spore-like pigmented yeast forms on Grocott's methenamine silver stain can suggest chromoblastomycosis, but this finding is not specific. By contrast, phaeohyphomycosis characteristically exhibits circumscribed pseudocyst or abscess on histopathology, and both yeast and hyphae can be seen. Our case reports a DCFI with pseudoepitheliomatous hyperplasia and "copper penny" yeast forms, ultimately diagnosed as phaeohyphomycosis after isolating Exophiala spinifera on fungal culture.

Orbital abscess caused by Exophiala dermatitidis following posterior subtenon injection of triamcinolone acetonide: a case report and a review of literature related to Exophiala eye infections

Background

Subtenon injection of triamcinolone acetonide (STTA) has been widely adopted in the clinical setting of ophthalmology and its infectious complications are rare. However, orbital abscess following STTA has been reported in seven cases. Furthermore, although eye infections due to Exophiala species are uncommon, there have been 19 cases to date. E. jeanselmei, E. phaeomuriformis, E. werneckii, and E. dermatitidis have been reported to cause human eye infections; however, to the best of our knowledge, orbital abscess caused by E. dermatitidis has not yet been reported. We describe the first documented case of fungal orbital abscess caused by E. dermatitidis following STTA. We also review the related literature of orbital abscess following STTA, as well as eye infections caused by the four Exophiala species.

Case presentation

The patient was a 69-year-old Japanese woman with diabetic mellitus. She had a macular oedema in her right eye, which occurred secondary to branch retinal vein occlusion. An orbital abscess caused by E. dermatitidis occurred 4 months after the second STTA for the macular oedema, which was successfully treated by a surgical debridement and systemic administration of voriconazole.

Conclusions

Our findings in the patient and from our literature survey caution ophthalmologists to the fact that STTA can cause fungal orbital infections, especially in diabetic patients. Furthermore, surgical treatment is one of the most important risk factors.

Exophiala dermatitidis Fungemia Diagnosed Using Time-of-flight Mass Spectrometry during Chemotherapy for Malignant Lymphoma and Successful Treatment with Voriconazole

Infectious diseases, including those caused by fungi, remain important issues in patients receiving malignant lymphoma chemotherapy. We herein report a rare case of Exophiala dermatitidis fungemia during chemotherapy in a 67-year-old woman admitted to our hospital. She had a fever that could not be resolved despite antifungal therapy. Yeast-like fungi were detected in blood culture samples, but biochemical identification was difficult. E. dermatitidis, a black mold, was identified using time-of-flight mass spectrometry. The patient finally improved after her treatment was switched to voriconazole. Fungal infection is difficult to diagnose and treat, but this novel approach can improve patients' outcomes.

Exophiala dermatitidis: Key issues of an opportunistic fungal pathogen

The black yeast Exophiala dermatitidis is an opportunistic pathogen, causing phaeohyphomycosis in immunosuppressed patients, chromoblastomycosis and fatal infections of the central nervous system in otherwise healthy Asian patients. In addition, it is also regularly isolated from respiratory samples from cystic fibrosis patients, with rates varying between 1% and 19%.Melanin, as part of the cell wall of black yeasts, is one major factor known contributing to the pathogenicity of E. dermatitidis and increased resistance against host defense and anti-infective therapeutics. Further virulence factors, e.g. the capability to adhere to surfaces and to form biofilm were reported. A better understanding of the pathogenicity of E. dermatitidis is essential for the development of novel preventive and therapeutic strategies. In this review, the current knowledge of E. dermatitidis prevalence, clinical importance, diagnosis, microbiological characteristics, virulence attributes, susceptibility, and resistances as well as therapeutically strategies are discussed.

Disseminated phaeohyphomycosis with hepatic artery and portal vein thrombosis caused by Pleurostomophora richardsiae in a liver transplant recipient: A case report

Pleurostomophora richardsiae is a dematiaceous mold that causes subcutaneous cystic phaeohyphomycosis. Few cases of invasive P richardsiae infection have been reported. Hepatic artery thrombosis following organ transplantation caused by a fungal organism is also very rare. We present here a 57-year-old man with refractory ascites and liver failure following liver transplantation for treatment of hepatocellular carcinoma. Abdominal computed tomography demonstrated total occlusion of hepatic artery and blood clot in the portal vein and inferior vena cava. P richardsiae was isolated from blood culture and the blood clot in his liver. The patient was treated successfully with a 4-week course of amphotericin B deoxycholate and liver retransplantation.

A fatal case of Exophiala dermatitidis disseminated infection in an allogenic hematopoietic stem cell transplant recipient during micafungin therapy

Exophiala dermatitidis is a dematiaceous fungus that is increasingly becoming the cause of fungal infection in immunocompromised patients. However, the risk factors and optimal treatment modality for E. dermatitidis infection are unknown to date. Herein, we present a fatal case of E. dermatitidis infection in an adult patient that developed after allogeneic hematopoietic stem cell transplantation for chronic active Epstein-Barr virus infection. The dematiaceous fungus caused a breakthrough fungemia despite prophylactic administration of micafungin. Although the patient was intensively treated with liposomal-amphotericin B and voriconazole, serum level of beta-D-glucan continuously increased, and the patient eventually died because of cerebral hemorrhage. An autopsy found multiple involvements of the fungal infection at the bilateral lungs, thoracic cavities, diaphragm, and thyroid. To the best of our knowledge, this is the first reported case of E. dermatitidis infection involving these tissues as determined via autopsy. This case highlights the importance of attention for Exophiala infection in immunocompromised individuals in those given antifungal therapy with echinocandins.