Mycetoma: Experience of 482 Cases in a Single Center in Mexico

Mycetoma is a chronic granulomatous disease. It is classified into eumycetoma caused by fungi and actinomycetoma due to filamentous actinomycetes. Mycetoma can be found in geographic areas in close proximity to the Tropic of Cancer. Mexico is one of the countries in which this disease is highly endemic. In this retrospective study we report epidemiologic, clinical and microbiologic data of mycetoma observed in the General Hospital of Mexico in a 33 year-period (1980 to 2013). A total of 482 cases were included which were clinical and microbiology confirmed. Four hundred and forty four cases (92.11%) were actinomycetomas and 38 cases (7.88%) were eumycetomas. Most patients were agricultural workers; there was a male predominance with a sex ratio of 3∶1. The mean age was 34.5 years old (most ranged from 21 to 40 years). The main affected localization was lower and upper limbs (70.74% and 14.52% respectively). Most of the patients came from humid tropical areas (Morelos, Guerrero and Hidalgo were the regions commonly reported). The main clinical presentation was as tumor-like soft tissue swelling with draining sinuses (97.1%). Grains were observed in all the cases. The principal causative agents for actinomycetoma were: Nocardia brasiliensis (78.21%) and Actinomadura madurae (8.7%); meanwhile, for eumycetomas: Madurella mycetomatis and Scedosporium boydii (synonym: Pseudallescheria boydii) were identified. This is a single-center, with long-follow up, cross-sectional study that allows determining the prevalence and characteristics of mycetoma in different regions of Mexico.     

Mycetoma: a clinical dilemma in resource limited settings

Background

Mycetoma is a chronic mutilating disease of the skin and the underlying tissues caused by fungi or bacteria. Although recently included in the list of neglected tropical diseases by the World Health Organization, strategic control and preventive measures are yet to be outlined. Thus, it continues to pose huge public health threat in many tropical and sub-tropical countries. If not detected and managed early, it results into gruesome deformity of the limbs. Its low report and lack of familiarity may predispose patients to misdiagnosis and delayed treatment initiation. More so in situation where diagnostic tools are limited or unavailable, little or no option is left but to clinically diagnose these patients. Therefore, an overview of clinical course of mycetoma, a suggested diagnostic algorithm and proposed use of materials that cover the exposed susceptible parts of the body during labour may assist in the prevention and improvement of its management. Furthermore, early reporting which should be encouraged through formal and informal education and sensitization is strongly suggested.

Main text

An overview of the clinical presentation of mycetoma in the early and late phases, clues to distinguish eumycetoma from actinomycetoma in the field and the laboratory, differential diagnosis and a suggested diagnostic algorithm that may be useful in making diagnosis amidst the differential diagnosis of mycetoma is given. Additionally, a proposed preventive measures which may be helpful in the community is also provided. Since treatment is currently based on expert opinion, we encourage active research to establish treatment guideline for it.

Conclusion

Since delay in visiting health facility results into gruesome complication, early presentation, recognition and initiation of appropriate choice of regimen is helpful in reducing complications. The clinical overview of mycetoma and the suggested algorithm may enhance suspicion and possibly increase recognition of mycetoma in the community and further guide in differentiation of eumycetoma from actinomycetoma. There is an urgent need for research funding for mycetoma, a disease plagued by severe physical disabilities and social stigma leading to isolation.

     

Merits and Pitfalls of Currently Used Diagnostic Tools in Mycetoma

Treatment of mycetoma depends on the causative organism and since many organisms, both actinomycetes (actinomycetoma) and fungi (eumycetoma), are capable of producing mycetoma, an accurate diagnosis is crucial. Currently, multiple diagnostic tools are used to determine the extent of infections and to identify the causative agents of mycetoma. These include various imaging, cytological, histopathological, serological, and culture techniques; phenotypic characterisation; and molecular diagnostics. In this review, we summarize these techniques and identify their merits and pitfalls in the identification of the causative agents of mycetoma and the extent of the disease. We also emphasize the fact that there is no ideal diagnostic tool available to identify the causative agents and that future research should focus on the development of new and reliable diagnostic tools.     

Cytodiagnosis of eumycotic mycetoma: a case report

BACKGROUND: Mycetoma is a late-stage clinical manifestation of a subcutaneous infection produced by bacteria (actinomycetoma) or fungi (eumycetoma). Only a few articles have described the morphologic appearance of this uncommon pathology on cytology. The distinction between eumycetoma and actinomycetoma in fine needle aspiration cytology (FNAC) is as accurate as in histopathology, as demonstrated in the present case. CASE: A 30-year-old man presented with a large swelling on his left foot with a discharging sinus. FNAC of the swelling yielded pus-like material. Initial Papanicolaou and Giemsa stains showed the presence of septate, branching fungal hyphae and black granules against the inflammatory background. The presence of fungus was confirmed by PAS stain. The species was identified as Exophiala jeanselmei on fungal culture. CONCLUSION: Mycotic mycetoma can be accurately diagnosed by FNAC, which is a simple, inexpensive and rapid technique when there is a high index of suspicion. Special stains and culture studies are helpful in confirmation of diagnosis and species identification.     

Mycetoma Medical Therapy

Medical treatment of mycetoma depends on its fungal or bacterial etiology. Clinically, these entities share similar features that can confuse diagnosis, causing a lack of therapeutic response due to inappropriate treatment. This review evaluates the response to available antimicrobial agents in actinomycetoma and the current status of antifungal drugs for treatment of eumycetoma.     

Head and Neck Mycetoma: The Mycetoma Research Centre Experience

Mycetoma is a unique neglected tropical disease which is endemic in what is known as the “mycetoma belt”. The disease has many devastating impacts on patients and communities in endemic area and is characterised by massive deformity, destruction and disability. Mycetoma is commonly seen in the foot and hand and less frequent in other parts of the body. Mycetoma of the head and neck is a rarity and is associated with high morbidity and even mortality if not treated early. In this communication we report on 49 patients with head and neck mycetoma followed up at the Mycetoma Research Centre in Khartoum. Most of the reported patients had actinomycetoma and the majority were young adult males from mycetoma endemic areas in the Sudan. Most of them were students, farmers and workers. Prior to presentation the majority had long disease duration and the cause was multifactorial. Advanced disease with massive lesion, deformity and disability was the common presentation. There was no obvious history of local trauma, familial tendency or other predisposing factor identified in this group of patients. MRI and CT scan were the most accurate diagnostic tools to determine the disease extent. The treatment outcome was rather poor and characterised by low cure rate, poor outcome and high follows-up dropout. Such a gloomy outcome calls for structured and objective health education programs.     

Systematic whole-genome sequencing reveals an unexpected diversity among actinomycetoma pathogens and provides insights into their antibacterial susceptibilities

Mycetoma is a neglected tropical chronic granulomatous inflammatory disease of the skin and subcutaneous tissues. More than 70 species with a broad taxonomic diversity have been implicated as agents of mycetoma. Understanding the full range of causative organisms and their antibiotic sensitivity profiles are essential for the appropriate treatment of infections. The present study focuses on the analysis of full genome sequences and antibiotic inhibitory concentration profiles of actinomycetoma strains from patients seen at the Mycetoma Research Centre in Sudan with a view to developing rapid diagnostic tests. Seventeen pathogenic isolates obtained by surgical biopsies were sequenced using MinION and Illumina methods, and their antibiotic inhibitory concentration profiles determined. The results highlight an unexpected diversity of actinomycetoma causing pathogens, including three Streptomyces isolates assigned to species not previously associated with human actinomycetoma and one new Streptomyces species. Thus, current approaches for clinical and histopathological classification of mycetoma may need to be updated. The standard treatment for actinomycetoma is a combination of sulfamethoxazole/trimethoprim and amoxicillin/clavulanic acid. Most tested isolates had a high IC (inhibitory concentration) to sulfamethoxazole/trimethoprim or to amoxicillin alone. However, the addition of the β-lactamase inhibitor clavulanic acid to amoxicillin increased susceptibility, particularly for Streptomyces somaliensis and Streptomyces sudanensis. Actinomadura madurae isolates appear to have a particularly high IC under laboratory conditions, suggesting that alternative agents, such as amikacin, could be considered for more effective treatment. The results obtained will inform future diagnostic methods for the identification of actinomycetoma and treatment.     

Pulmonary Madurella mycetomatis mycetoma secondary to knee eumycetoma,Senegal

Mycetoma is a neglected tropical disease which is endemic in Senegal. Although this subcutaneous mycosis is most commonly found on the foot, extrapodal localisations have also been found, including on the leg, knee, thigh, hand, and arm. To our knowledge, no case of blood-spread eumycetoma has been reported in Senegal. Here, we report a case of pulmonary mycetoma secondary to a Madurella mycetomatis knee eumycetoma. The patient was a 41-year-old farmer living in Louga, Senegal, where the Sudano-Sahelian climate is characterised by a short and unstable rainy season and a steppe vegetation. He suffered a trauma to the right more than 20 years previously and had received treatment for more than 10 years with traditional medicine. He consulted at Le Dantec University Hospital in Dakar for treatment of a right knee mycetoma which had been diagnosed more than 10 years ago. He had experienced a chronic cough for more than a year; tuberculosis documentation was negative. Grains collected from the knee and the sputum isolated M. mycetomatis, confirmed by the rRNA gene ITS regions nucleotide sequence analysis. An amputation above the knee was performed, and antibacterial and antifungal therapy was started with amoxicillin-clavulanic acid and terbinafine. The patient died within a month of his discharge from hospital.     

Mycetoma in the Sudan: An Update from the Mycetoma Research Centre,University of Khartoum,Sudan

This communication reports on the Mycetoma Research Centre of the University of Khartoum, Sudan experience on 6,792 patients seen during the period 1991–2014.The patients were predominately young (64% under 30 years old) males (76%). The majority (68%) were from the Sudan mycetoma belt and 28% were students. Madurella mycetomatis eumycetoma was the most common type (70%). In 66% of the patients the duration of the disease was less than five years, and 81% gave a history of sinuses discharging mostly black grains (78%). History of trauma at the mycetoma site was reported in 20%. Local pain was reported in 27% of the patients, and only 12% had a family history of mycetoma. The study showed that 57% of the patients had previous surgical excisions and recurrence, and only 4% received previous medical treatment for mycetoma. Other concomitant medical diseases were reported in 4% of the patients. The foot (76%) and hand (8%) were the most commonly affected sites. Less frequently affected sites were the leg and knee (7%), thigh (2%), buttock (2%) and arm and forearm (1%). Rare sites included the chest wall, head and neck, back, abdominal wall, perineum, oral cavity, tongue and eye. Multiple sites mycetoma was recorded in 135 (2%) of cases. At presentation, 37% of patients had massive lesions, 79% had sinuses, 8% had local hyper-hydrosis at the mycetoma lesion, 11% had regional lymphadenopathy, while 6% had dilated tortuous veins proximal to the mycetoma lesions. The diagnosis of mycetoma was established by combined imaging techniques and cytological, histopathological, serological tests and grain culture. Patients with actinomycetoma received a combination of antimicrobial agents, while eumycetoma patients received antifungal agents combined with various surgical excisions. Surgical excisions in the form of wide local excision, debridement or amputation were done in 807 patients, and of them 248 patients (30.7%) had postoperative recurrence. Different types of amputations were done in 120 patients (1.7%).     

Screening the pandemic response box identified benzimidazole carbamates,Olorofim and ravuconazole as promising drug candidates for the treatment of eumycetoma

Eumycetoma is a chronic subcutaneous neglected tropical disease that can be caused by more than 40 different fungal causative agents. The most common causative agents produce black grains and belong to the fungal orders Sordariales and Pleosporales. The current antifungal agents used to treat eumycetoma are itraconazole or terbinafine, however, their cure rates are low. To find novel drugs for eumycetoma, we screened 400 diverse drug-like molecules from the Pandemic Response Box against common eumycetoma causative agents as part of the Open Source Mycetoma initiative (MycetOS). 26 compounds were able to inhibit the growth of Madurella mycetomatis, Madurella pseudomycetomatis and Madurella tropicana, 26 compounds inhibited Falciformispora senegalensis and seven inhibited growth of Medicopsis romeroi in vitro. Four compounds were able to inhibit the growth of all five species of fungi tested. They are the benzimidazole carbamates fenbendazole and carbendazim, the 8-aminoquinolone derivative tafenoquine and MMV1578570. Minimal inhibitory concentrations were then determined for the compounds active against M. mycetomatis. Compounds showing potent activity in vitro were further tested in vivo. Fenbendazole, MMV1782387, ravuconazole and olorofim were able to significantly prolong Galleria mellonella larvae survival and are promising candidates to explore in mycetoma treatment and to also serve as scaffolds for medicinal chemistry optimisation in the search for novel antifungals to treat eumycetoma.     

Antifungal Activity of Natural Naphthoquinones and Anthraquinones against Madurella mycetomatis

Eumycetoma, the fungal form of the neglected tropical disease mycetoma, is a crippling infectious disease with low response rates to currently available antifungal drugs. In this study, a series of natural naphthoquinones and anthraquinones was evaluated for their activity against Madurella mycetomatis, which is the most common causative agent of eumycetoma. The metabolic activity of Madurella mycetomatis as well as the viability of Galleria mellonella larvae upon treatment with quinones was investigated. Several hydroxy-substituted naphthoquinones exhibited activity against Madurella mycetomatis. In particular, naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) was identified as a considerably active antifungal compound against Madurella mycetomatis (IC₅₀=1.4 μM), while it showed reduced toxicity to Galleria mellonella larvae, which is a well-established in vivo invertebrate model for mycetoma drug studies.     

Mycetomas in Iran: a review article

Mycetomas are the subcutaneous and relatively rare chronic pustular infections. The etiologic agents of mycetomas are a group of saprophytic fungi and actinomycetes living in soil. We retrospectively discussed the overall prevalence of mycetomas and the prevalence of infective agents in Iran between 1972 and 2005. Seventy-six cases of mycetomas have been reported from various geographical locations in Iran during 33 years. Analysis of the records revealed that 84.5% were actinomycetoma and only 15.5% were eumycetoma. Disease mainly has been seen in foot, and the male to female ratio was 2:1. Mycetomas were abundant among farmers in rural areas of Iran. The commonest agents of mycetomas were Nocardia asteroids, Actinomadura madura (actinomycetoma) and Allesheria boydii (eumycetoma). The peak age of onset was between 31 and 51 years.     

Eumycetoma of the Hand Caused by <Emphasis Type="Italic">Leptosphaeria tompkinsii</Emphasis> and Refractory to Medical Therapy with Voriconazole

We report on the first case of eumycetoma caused by the organism Leptosphaeria tompkinsii to be diagnosed and possibly acquired within the United Kingdom. Conventional culture of fungal grains and surgical tissue specimens was negative and the diagnosis was achieved using panfungal polymerase chain reaction and sequencing technology. Despite limited surgical resection and prolonged antifungal therapy with voriconazole, the patient developed progressive disease with mycetoma bone involvement. This case highlights the usefulness of molecular diagnostic techniques in eumycetoma where organisms may fail to grow with conventional culture or be difficult to identify morphologically. It also reminds us that eumycetoma is a difficult infection to treat and despite optimism regarding the efficacy of the newer triazole antifungals in this condition, treatment failures may still occur.     

Mapping the Potential Risk of Mycetoma Infection in Sudan and South Sudan Using Ecological Niche Modeling

In 2013, the World Health Organization (WHO) recognized mycetoma as one of the neglected tropical conditions due to the efforts of the mycetoma consortium. This same consortium formulated knowledge gaps that require further research. One of these gaps was that very few data are available on the epidemiology and transmission cycle of the causative agents. Previous work suggested a soil-borne or Acacia thorn-prick-mediated origin of mycetoma infections, but no studies have investigated effects of soil type and Acacia geographic distribution on mycetoma case distributions. Here, we map risk of mycetoma infection across Sudan and South Sudan using ecological niche modeling (ENM). For this study, records of mycetoma cases were obtained from the scientific literature and GIDEON; Acacia records were obtained from the Global Biodiversity Information Facility. We developed ENMs based on digital GIS data layers summarizing soil characteristics, land-surface temperature, and greenness indices to provide a rich picture of environmental variation across Sudan and South Sudan. ENMs were calibrated in known endemic districts and transferred countrywide; model results suggested that risk is greatest in an east-west belt across central Sudan. Visualizing ENMs in environmental dimensions, mycetoma occurs under diverse environmental conditions. We compared niches of mycetoma and Acacia trees, and could not reject the null hypothesis of niche similarity. This study revealed contributions of different environmental factors to mycetoma infection risk, identified suitable environments and regions for transmission, signaled a potential mycetoma-Acacia association, and provided steps towards a robust risk map for the disease.     

Detection of multiple mycetoma pathogens using fungal metabarcoding analysis of soil DNA in an endemic area of Sudan

Mycetoma is a tropical disease caused by several fungi and bacteria present in the soil. Fungal mycetoma and eumycetoma are especially challenging to treat; therefore, prevention, early diagnosis, and early treatment are important, but it is also necessary to understand the geographic distribution of these pathogenic fungi. In this study, we used DNA metabarcoding methodology to identify fungal species from soil samples. Soil sampling was implemented at seven villages in an endemic area of Sennar State in Sudan in 2019, and ten sampling sites were selected in each village according to land-use conditions. In total, 70 soil samples were collected from ground surfaces, and DNA in the soil was extracted with a combined method of alkaline DNA extraction and a commercial soil DNA extraction kit. The region for universal primers was selected to be the ribosomal internal transcribed spacer one region for metabarcoding. After the second PCR for DNA library preparation, the amplicon-based DNA analysis was performed using next-generation sequencing with two sets of universal primers. A total of twelve mycetoma-causative fungal species were identified, including the prime agent, Madurella mycetomatis, and additional pathogens, Falciformispora senegalensis and Falciformispora tompkinsii, in 53 soil samples. This study demonstrated that soil DNA metabarcoding can elucidate the presence of multiple mycetoma-causative fungi, which may contribute to accurate diagnosis for patient treatment and geographical mapping.     

The In Vitro Antifungal Activity of Sudanese Medicinal Plants against Madurella mycetomatis,the Eumycetoma Major Causative Agent

Eumycetoma is a debilitating chronic inflammatory fungal infection that exists worldwide but it is endemic in many tropical and subtropical regions. The major causative organism is the fungus Madurella mycetomatis. The current treatment of eumycetoma is suboptimal and characterized by low cure rate and high recurrence rates. Hence, an alternative therapy is needed to address this. Here we determined the antifungal activity of seven Sudanese medicinal plant species against Madurella mycetomatis. Of these, only three species; Boswellia papyrifera, Acacia nubica and Nigella sativa, showed some antifungal activity against M. mycetomatis and were further studied. Crude methanol, hexane and defatted methanol extracts of these species were tested for their antifungal activity. B. papyrifera had the highest antifungal activity (MIC50 of 1 ug/ml) and it was further fractionated. The crude methanol and the soluble ethyl acetate fractions of B. papyrifera showed some antifungal activity. The Gas-Liquid-Chromatography hybrid Mass-Spectrophotometer analysis of these two fractions showed the existence of beta-amyrin, beta-amyrone, beta-Sitosterol and stigmatriene. Stigmatriene had the best antifungal activity, compared to other three phytoconstituents, with an MIC-50 of 32 μg/ml. Although the antifungal activity of the identified phytoconstituents was only limited, the antifungal activity of the complete extracts is more promising, indicating synergism. Furthermore these plant extracts are also known to have anti-inflammatory activity and can stimulate wound-healing; characteristics which might also be of great value in the development of novel therapeutic drugs for this chronic inflammatory disease. Therefore further exploration of these plant species in the treatment of mycetoma is encouraging.     

A Call to Action for Mycetoma

Purpose of Review

Here, we discuss the current needs and priorities for mycetoma control and prevention, highlight lessons learned from leprosy and podoconiosis, and motivate an urgent need to accelerate progress toward reducing the burden of mycetoma in endemic areas.

Recent Findings

In 2015, the World Health Assembly (WHA) added mycetoma, a progressively debilitating disease caused by fungi and bacteria, to the World Health Organization (WHO) list of priority neglected tropical diseases (NTDs). Designation of other diseases as NTDs has raised awareness, enabled global partnerships, and advanced the capacity to combat disease through integrated programming. Although key mycetoma etiologic agents have been identified, many questions remain and mycetoma may similarly benefit from NTD designation.

Summary

In collaboration with experts at WHO and elsewhere, we formed a global mycetoma working group to connect partners from a variety of sectors and specialties. We envision that this group will evolve into a formalized partnership that can prioritize strategic planning, advocacy, and research needs, identify funding sources, and coordinate activities related to mycetoma and other NTDs affecting the skin. The experiences gained from other NTDs can help to guide the global mycetoma working group’s activities to better address the goals set forth in the WHA resolution.

     

Rapid Identification of Black Grain Eumycetoma Causative Agents Using Rolling Circle Amplification

Accurate identification of mycetoma causative agent is a priority for treatment. However, current identification tools are far from being satisfactory for both reliable diagnosis and epidemiological investigations. A rapid, simple, and highly efficient molecular based method for identification of agents of black grain eumycetoma is introduced, aiming to improve diagnostic in endemic areas. Rolling Circle Amplification (RCA) uses species-specific padlock probes and isothermal DNA amplification. The tests were based on ITS sequences and developed for Falciformispora senegalensis, F. tompkinsii, Madurella fahalii, M. mycetomatis, M. pseudomycetomatis, M. tropicana, Medicopsis romeroi, and Trematosphaeria grisea. With the isothermal RCA assay, 62 isolates were successfully identified with 100% specificity and no cross reactivity or false results. The main advantage of this technique is the low-cost, high specificity, and simplicity. In addition, it is highly reproducible and can be performed within a single day.