Seventeen years of subcutaneous infection byAspergillus flavus; eumycetoma confirmed by immunohistochemistry

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.

The Molecular Identification and Antifungal Susceptibility of Clinical Isolates of Aspergillus Section Flavi from Three French Hospitals

(1) Background: Aspergillus flavus is a cosmopolitan mold with medical, veterinary, and agronomic concerns. Its morphological similarity to other cryptic species of the Flavi section requires molecular identification techniques that are not routinely performed. For clinical isolates of Aspergillus section Flavi, we present the molecular identification, susceptibility to six antifungal agents, and clinical context of source patients. (2) Methods: One hundred forty fungal clinical isolates were included in the study. These isolates, recovered over a 15-year period (2001-2015), were identified based on their morphological characteristics as belonging to section Flavi. After the subculture, sequencing of a part of the β-tubulin and calmodulin genes was performed, and resistance to azole antifungals was screened on agar plates containing itraconazole and voriconazole. Minimum inhibitory concentrations were determined for 120 isolates by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. (3) Results: Partial β-tubulin and calmodulin sequences analysis showed that 138/140 isolates were A. flavus sensu stricto, 1 isolate was A. parasiticus/sojae, and 1 was A. nomiae. Many of the isolates came from samples collected in the context of respiratory tract colonization. Among probable or proven aspergillosis, respiratory infections were the most frequent, followed by ENT infections. Antifungal susceptibility testing was available for isolates (n = 120, all A. flavus ss) from one hospital. The MIC range (geometric mean MIC) in mg/L was 0.5-8 (0.77), 0.5-8 (1.03), 0.125-2 (0.25), 0.03-2 (0.22), 0.25-8 (1.91), and 0.03-0.125 (0.061) for voriconazole, isavuconazole, itraconazole, posaconazole, amphotericin B, and caspofungin, respectively. Two (1.67%) isolates showed resistance to isavuconazole according to current EUCAST breakpoints with MICs at 8 mg/L for isavuconazole and voriconazole. One of these two isolates was also resistant to itraconazole with MIC at 2 mg/L. (4) Conclusions: The present characterization of a large collection of Aspergillus belonging to the Flavi section confirmed that A. flavus ss is the predominant species. It is mainly implicated in respiratory and ENT infections. The emergence of resistance highlights the need to perform susceptibility tests on section Flavi isolates.

Mycetoma due to Aspergillus flavus in a diabetic patient: Case report and literature review

Diabetes mellitus patients are prone to cutaneous and subcutaneous fungal infections due to pathogenic fungi, including dermatophytes, Mucorales, Candida, Aspergillus, and Fusarium species. Here, we report a case of A. flavus mycetoma confirmed by isolation and molecular identification. The case was a 38-year-old male farmer with a seven-year history of type 2 diabetes mellitus, living in Khuzestan, southwest of Iran. The patient presented with a right foot swelling associated with a nodule and multiple discharging sinuses following trauma sustained on the foot while working barefoot on the rice farm, a year ago. The nodule appeared at the site of the trauma two months after the injury. The initial diagnosis was based on direct microscopic examination of lesions scraping using 20% potassium hydroxide and radiology. Molecular analysis confirmed the isolates to be A. flavus. In vitro susceptibility of the isolate to voriconazole, posaconazole, caspofungin, itraconazole, and amphotericin B was determined. Treatment with voriconazole (200 mg twice daily) stopped the purulent discharge, reduced the swelling, and improved the clinical condition within two months. The study emphasizes the importance of wearing footwear to prevent skin trauma as the main risk factor of patient involvement.

Mycetoma caused by Microascus gracilis: a novel agent of human eumycetoma in Sudan

Species of the genus Microascus are uncommon agents of human diseases despite their ubiquitous presence in the environment. In this communication, the first case of white grain eumycetoma caused by the fungus Microascus gracilis is reported. The patient was initially misdiagnosed as having actinomycetoma based on the grains morphological and cytological features and was treated with antimicrobial therapy with no clinical improvement. She underwent wide local surgical excision to improve the response to medical treatment and further grain cultural, molecular and taxonomy techniques were conducted and the diagnosis of mycetoma due to M. gracilis was established. The antifungal susceptibilities of this isolate to nine drugs were tested in vitro and they showed poor activity. Combination therapy with surgery and itraconazole led to complete recovery. A medical literature search revealed no previous report on M. gracilis as a causative agent of eumycetoma and hence we are reporting this new causative agent of human eumycetoma. Also, the difficulty in the management of this patient emphasizes the need for accurate and appropriate diagnostic tests for the identification of mycetoma-causative organisms and thus proper management.

Aspergillus candidus eumycetoma with review of literature

OBJECTIVE

Mycetoma is a slowly progressive, chronic granulomatous infection of skin and subcutaneous tissues with involvement of underlying fasciae and bones, usually affecting extremities. In India, among mycetoma, the eumycetoma constitutes about 35% of cases. Hereby, we report the first case of eumycetoma caused by uncommon fungus, Aspergillus candidus.

CASE REPORT

A 61 year old female presented to the Department of Dermatology with history of swelling of right foot associated with multiple firm nodules of approx. 1.5 × 1.5 cm each over dorsum of foot with discharging sinus containing white color granules. Biopsy of lesion on right foot on direct KOH examination revealed septate hyphae. Histopathology examination showed a histiocytic granuloma with fungal elements. Culture on Sabouraud Dextrose Agar grew white mycelial colonies which were identified to be Aspergillus species phenotypically. Genetic sequencing using Internal transcribed spacer gene, beta tubulin gene and Calmodulin gene was done and the isolate was identified to be Aspergillus candidus. Lesion was excised and patient was started on itraconazole.

CONCLUSION

Timely identification and starting of antifungal treatment can help in reducing morbidity due to eumycetoma to a large extent. As newer and newer species of fungi are emerging as significant causative agents of human infections, it is pertinent to report such findings from epidemiological point of view.

Eumycetoma of the Foot due to Fusarium solani in a Person with Diabetes Mellitus: Report of a Case and Review of Literature

Eumycetomas are chronic suppurative granulomas caused by fungi characterised by invasive tumefactive lesions, sinuses and discharging grains. Herein, we describe a case of pedal eumycetoma due to Fusarium solani sensu stricto in a person with diabetes mellitus. A 45-year-old gentleman presented with an insidious onset swelling over his right foot with nodules and discharging grains. He had received itraconazole and anti-tuberculous therapy elsewhere, without response. Re-evaluation included a biopsy which confirmed eumycetoma and newly diagnosed diabetes. Surgical excision followed by histopathological, microbiological and multigene sequencing analyses [translation elongation factor, calmodulin and internal transcribed spacer region of rDNA] of the mould on culture were performed. Histopathology revealed septate fungal hyphae amidst a dense inflammatory infiltrate (Splendore-Hoeppli) reaction. Oral voriconazole was started and good glycemic control attained. Tissue growth sequences showed > 99% similarity with Fusarium solani sensu stricto. Antifungal susceptibility testing showed lowest MIC to voriconazole (0.5 mg/L). The patient showed excellent response to combined therapeutic modality with a near-complete resolution in size of lesion and obliteration of sinuses following 4 months of therapy and is planned for prolonged voriconazole therapy till complete radiological resolution. Diabetes predisposes to fungal infections of foot but eumycetomas are uncommon. Combined surgery and antifungals can improve morbidity and avoid amputations.

Chaetomium atrobrunneum causing human eumycetoma: The first report

In this communication, a case of black grain eumycetoma produced by the fungus C. atrobrunneum is reported. The patient was initially misdiagnosed with M. mycetomatis eumycetoma based on the grains’ morphological and cytological features. However, further aerobic culture of the black grains generated a melanised fungus identified as C. atrobrunneum by conventional morphological methods and by internal transcribed spacer 2 (ITS2) ribosomal RNA gene sequencing. This is the first-ever report of C. atrobrunneum as a eumycetoma-causative organism of black grain eumycetoma. It is essential that the causative organism is identified to the species level, as this is important for proper patient management and to predict treatment outcome and prognosis.

Closing the mycetoma knowledge gap

On 28th May 2016, mycetoma was recognized as a neglected tropical disease by the World Health Organization. This was the result of a 4-year journey starting in February 2013 with a meeting of global mycetoma experts. Knowledge gaps were identified and included the incidence, prevalence, and mapping of mycetoma; the mode of transmission; the development of methods for early diagnosis; and better treatment. In this review, we review the road to recognition, the ISHAM working group meeting in Argentina, and we address the progress made in closing the knowledge gaps since 2013. Progress included adding another 9000 patients to the literature, which allowed us to update the prevalence map on mycetoma. Furthermore, based on molecular phylogeny, species names were corrected and four novel mycetoma causative agents were identified. By mapping mycetoma causative agents an association with Acacia trees was found. For early diagnosis, three different isothermal amplification techniques were developed, and novel antigens were discovered. To develop better treatment strategies for mycetoma patients, in vitro susceptibility tests for the coelomycete agents of black grain mycetoma were developed, and the first randomized clinical trial for eumycetoma started early 2017.

Recent advances on topical antimicrobials for skin and soft tissue infections and their safety concerns

Antimicrobial resistance of disease-related microorganisms is considered a worldwide prevalent and serious issue which increases the failure of treatment outcomes and leads to high mortality. Considering that the increased resistance to systemic antimicrobial therapy often needs of the use of more toxic agents, topical antimicrobial therapy emerges as an attractive route for the treatment of infectious diseases. The topical antimicrobial therapy is based on the absorption of high drug doses in a readily accessible skin surface, resulting in a reduction of microbial proliferation at infected skin sites. Topical antimicrobials retain the following features: (a) they are able to escape the enzymatic degradation and rapid clearance in the gastrointestinal tract or the first-pass metabolism during oral administration; (b) alleviate the physical discomfort related to intravenous injection; (c) reduce possible adverse effects and drug interactions of systemic administrations; (d) increase patient compliance and convenience; and (e) reduce the treatment costs. Novel antimicrobials for topical application have been widely exploited to control the emergence of drug-resistant microorganisms. This review provides a description of antimicrobial resistance, common microorganisms causing skin and soft tissue infections, topical delivery route of antimicrobials, safety concerns of topical antimicrobials, recent advances, challenges and future prospective in topical antimicrobial development.

Fusarium species causing eumycetoma: Report of two cases and comprehensive review of the literature

Recently, mycetoma was added to the World Health Organization's list of neglected tropical disease priorities. Fusarium as a genus has been reported to cause eumycetoma, but little is known about the species involved in this infection and their identification. In this study, molecular tools were applied to identify Fusarium agents from human eumycetoma cases. The partial translation elongation factor 1-alpha (TEF-1α) gene was used as diagnostic parameter. Two additional cases of eumycetoma, due to F. keratoplasticum and F. pseudensiforme, respectively, are presented. A systematic literature review was performed to assess general features, identification, treatment and outcome of eumycetoma infections due to Fusarium species. Of the 20 reviewed patients, the majority (75%) were male. Most agents belonged to the F. solani species complex, ie F. keratoplasticum, F. pseudensiforme, and an undescribed lineage of F. solani. In addition, F. thapsinum, a member of Fusarium fujikuroi species complex was encountered. The main antifungal drugs used were itraconazole, ketoconazole and amphotericin B, but cure rates were low (15%). Partial response or relapse was observed in some cases, and a case ended in amputation. Clinical management of eumycetoma due to Fusarium is complex and combination therapy might be required to increase cure rates.

Molecular identification of unusual Mycetoma agents isolated from patients in Venezuela

Mycetoma is a chronic granulomatous, subcutaneous disease endemic in tropical and subtropical countries. It is currently a health problem in rural areas of Africa, Asia and South America. Nine cases of mycetoma were analysed in a retrospective study. All isolates were identified by morphological features. The level of species identification was reached by molecular tools. Definitive identification of fungi was performed using sequence analysis of the ITS of the ribosomal DNA region and the ribosomal large-subunit D1/D2. Identification of actinomycetes was accomplished by the 16S rRNA gene sequence. Six unusual clinical isolates were identified: Aspergillus ustus, Cyphellophora oxyspora, Exophiala oligosperma, Madurella pseudomycetomatis, Nocardia farcinica and Nocardia wallacei. The prevalence of mycetoma in Venezuela remains unknown. This study represents the first report in the literature of mycetoma caused by unusual pathogens identified by molecular techniques.