Combination of Amphotericin B and Terbinafine against Melanized Fungi Associated with Chromoblastomycosis

Resazurin to determine the minimum inhibitory concentration on antifungal susceptibility assays for Fonsecaea sp. using a modified EUCAST protocol

Chromoblastomycosis is a fungal chronic disease, which affects humans, especially in cutaneous and subcutaneous tissues. There is no standard treatment for Chromoblastomycosis, and it is a therapeutic challenge, due natural resistance of their causative agents, inadequate response of patients and common cases of relapse. Protocols for determination of antifungal drugs susceptibility are not standardized for chromoblastomycosis agents and endpoint definition is usually based on visual inspection, which depends on the analyst, making it sometimes inaccurate. We presented a colorimetric and quantitative methodology based on resazurin reduction to resofurin to determine the metabolic status of viable cells of Fonsecaea sp. Performing antifungal susceptibility assay by a modified EUCAST protocol allied to resazurin, we validated the method to identify the minimum inhibitory concentrations of itraconazole, fluconazole, amphotericin B, and terbinafine for eight Fonsecaea clinical isolates. According to our data, resazurin is a good indicator of metabolic status of viable cells, including those exposed to antifungal drugs. This work aimed to test resazurin as an indicator of the metabolic activity of Fonsecaea species in susceptibility assays to antifungal drugs. Species of this genus are the main causative agents of Chromoblastomycosis, which affects humans.

Diagnosis of Cutaneous Chromoblastomycosis and Its Response to Amphotericin B Therapy: A Case Report

Cutaneous chromoblastomycosis is a chronic subcutaneous fungal disease of the skin caused by Blastomyces dermatitidis, especially by Fonsecaea, Phialophora,and Cladophialophora species affecting the skin, lungs, intestines, stomach, and central nervous system. It is treated using itraconazole in mild cases and amphotericin B in severe cases. A six-year-old female child presented to the Dermatology Outpatient Department with pigmented brown to blackish tanned plaques and verrucous lesions on the face and extremities. These lesions were present for the past two and a half years and were slowly enlarging and involving other areas like the trunk. The lesions were proven on biopsy to be cutaneous blastomycosis. The patient was put on infusions of amphotericin B in a calculated pediatric dose. Her blood pressure and renal function tests were checked daily to avoid any electrolyte derangements, nephrotoxicity, and systemic infusion reactions caused by amphotericin B. Amphotericin B reduced the size of the cutaneous lesions, and treatment response was assessed on regular follow-ups. Chromoblastomycosis should be considered in the differential diagnosis to enable timely treatment and to prevent its lethal complications such as epidermoid carcinoma. Treatment should continue for two to three months until histopathology is negative to ensure complete eradication.

The convoluted process of diagnosing pulmonary mycosis caused by Exophiala dermatitidis: a case report

Background

Etiological diagnosis is a key step in the treatment of patients with rare pulmonary mycosis, and the lack of understanding of this disease and lack of specific markers for the detection of rare species, such as Exophiala dermatitidis, add to the difficulty in diagnosing the condition. Therefore, improving the diagnostic strategies for this disease is very important.

Case presentation

A 52-year-old man presented with cough, sputum production and hemoptysis; chest computed tomography (CT) revealed multiple bilateral lesions. The pathogen was unable to be identified after three biopsies. Subsequently, we performed combined tissue metagenomic next-generation sequencing (mNGS). The results of mNGS and a good therapeutic response helped to identify the causative pathogen as Exophiala dermatitidis. Finally, the patient was diagnosed with Exophiala dermatitidis pneumonia.

Conclusions

Combining molecular techniques, such as mNGS, with clinical microbiological tests will improve the rate of positivity in the diagnosis of rare fungal infections, and the importance of follow-up should be emphasized.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07399-y.

Aspartic peptidase of Phialophora verrucosa as target of HIV peptidase inhibitors: blockage of its enzymatic activity and interference with fungal growth and macrophage interaction

Phialophora verrucosa causes several fungal human diseases, mainly chromoblastomycosis, which is extremely difficult to treat. Several studies have shown that human immunodeficiency virus peptidase inhibitors (HIV-PIs) are attractive candidates for antifungal therapies. This work focused on studying the action of HIV-PIs on peptidase activity secreted by P. verrucosa and their effects on fungal proliferation and macrophage interaction. We detected a peptidase activity from P. verrucosa able to cleave albumin, sensitive to pepstatin A and HIV-PIs, especially lopinavir, ritonavir and amprenavir, showing for the first time that this fungus secretes aspartic-type peptidase. Furthermore, lopinavir, ritonavir and nelfinavir reduced the fungal growth, causing remarkable ultrastructural alterations. Lopinavir and ritonavir also affected the conidia-macrophage adhesion and macrophage killing. Interestingly, P. verrucosa had its growth inhibited by ritonavir combined with either itraconazole or ketoconazole. Collectively, our results support the antifungal action of HIV-PIs and their relevance as a possible alternative therapy for fungal infections.

Synergistic effect of terbinafine and amphotericin B in killing Fonsecaea nubica in vitro and in vivo

Chromoblastomycosis is a chronic fungal infection. Itraconazole and terbinafine are the most recommended antifungal drugs for chromoblastomycosis, while amphotericin B is not usually recommended. A patient with chromoblastomycosis in our hospital showed poor clinical responses to itraconazole and terbinafine. The fungus isolated from the lesions of this patient was identified as Fonsecaea nubica and numbered zssy0803. In vitro antifungal susceptibilities of F. nubica zssy0803 to terbinafine, amphotericin B, itraconazole, voriconazole and caspofungin were evaluated, as well as the combinations of terbinafine with the other four antifungals. The combined effect of terbinafine and amphotericin B on other 20 clinical F. nubica strains was also evaluated. The minimal inhibitory concentrations of terbinafine, amphotericin B, itraconazole, voriconazole and caspofungin on F. nubica zssy0803 were 0.25 μg/mL, 2 μg/mL, 1 μg/mL, 4 μg/mL and 8 μg/mL, respectively. The combination of terbinafine and amphotericin B showed the lowest fractional inhibitory concentration index of 0.28 to F. nubica zssy0803 in comparison with combinations of terbinafine and the other four antifungal drugs. The combination of terbinafine and amphotericin B was also synergistic for all the other 20 F. nubica strains. Then, the combination of oral terbinafine (500 mg/day) and intralesional injections of amphotericin B (1 mg/mL) was used to treat this patient. After this combined therapy for 25 weeks and terbinafine monotherapy for additional 12 weeks, the patient was cured. These findings indicate for the first time that terbinafine and amphotericin B are synergistic in killing F. nubica both in vitro and in vivo.

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.

Global guidelines and initiatives from the European Confederation of Medical Mycology to improve patient care and research worldwide: New leadership is about working together

Invasive mycoses present a global challenge with expansion into new hosts, emergence of new pathogens, and development of multidrug resistance. In parallel, new antifungal agents and advanced laboratory diagnostic systems are being developed. In response to these evolving challenges, the European Confederation of Medical Mycology (ECMM) is committed to providing international expertise, guidance, and leadership with the key objectives of improving diagnosis, treatment, outcome, and survival of persons with invasive fungal diseases. Representing 25 affiliated National Medical Mycology Societies, the ECMM has developed several major ways to achieving these critical objectives: (a) tasking specific medical mycology working groups; (b) founding the ECMM Academy and Fellow program (FECMM); (c) expanding the goals of ECMM beyond the European region; (d) implementing the ECMM Excellence Centre Initiative in Europe; and (e) the ECMM Global Guidelines and Neglected Orphan Disease Guidance Initiatives focusing on mucormycosis, rare mould diseases, rare yeast diseases, and endemic mycoses. We believe that these important initiatives and other strategies of the ECMM will advance the field of medical mycology and improve the outcome of patients with invasive mycoses worldwide.