Mycetoma fungal infection: multiple organisms as colonizers or pathogens?

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.

Mycetoma, a chronic subcutaneous and cutaneous disease, designated as a "neglected tropical disease," is prevalent in dry and hot climates. Fungal mycetoma is caused by more than 50 species of soil-dwelling pathogenic fungi, and its diagnosis and treatment can be challenging. The prevention of infection and early diagnosis and treatment are essential, and for this purpose, environmental assessment to understand the fungal habitat is necessary. In this study, we performed DNA metabarcoding analysis using next-generation sequencing (NGS) for mycetoma pathogens from environmental soil samples in Sudan. The results suggest that multiple causative agents of fungal mycetoma are widespread regardless of the environment and can be a source of infection anywhere in an endemic area. Based on the results of this study, we expect that the investigation of fungi in soil using NGS technology may help identify infection routes and create risk maps for the prevention of mycetoma.

Cranial Mycetoma: A Rare Case Report with Review of Literature

Mycetoma is a chronic granulomatous infection caused by fungi or bacteria, known as eumycetoma and actinomycetoma, respectively. Mycetoma commonly affects young males belonging to low socioeconomic strata, usually barefooted agricultural workers. It mainly affects lower and upper limbs presenting as a painless swelling with discharging sinus. Rarely, is it encountered in the intracranial location. The diagnosis relies on the clinical presentation and identification of the etiological agents within the tissue, by histology and special stains. It is important to specify the fungal or bacterial etiology, because the treatment of each is completely different. The management of such infections is challenging and should involve early diagnosis, the use of antibacterials or antifungals, and surgical removal of the lesion. To the best of our knowledge, only seven cases of intracranial mycetoma have been reported. The present case highlights the rarity of this lesion, thereby contributing to the existing literature and presenting its diagnostic implications.

Treatment of Madura foot: a systematic review

REVIEW QUESTION/OBJECTIVE

The objective of this review was to determine the best available evidence on the most effective treatment of Madura foot.

INTRODUCTION

Madura foot or mycetoma is a chronic granulomatous soft-tissue infection that is endemic to several regions of Africa and Asia. It may be of fungal (eumycetoma) or bacterial (actinomycetoma) origin, warranting therapy with either antifungal or antibacterial medication as well as surgery. Without timely intervention, it often results in lifelong disability. However, it is unclear what regimes are most effective for treatment.

INCLUSION CRITERIA

This review considered studies that included individuals of all ages with Madura foot (actinomycetoma or eumycetoma) as confirmed by microbiological or histological studies. Studies that evaluated antibiotic and antifungal regimens (any drug, dosage, frequency, duration) as well as surgical interventions (wound debridement, advanced excision or limb amputation) for Madura foot were included. Outcomes of interest were disease resolution (as determined by complete healing of mycetoma lesion after treatment), recurrence (return of mycetoma lesion after successful treatment) and mortality. Although this review considered both experimental and epidemiological study designs for inclusion, only case series and individual case reports were identified and were therefore included in the review.

METHODS

A three-step search strategy, involving an initial search, a second more comprehensive search using identified keywords and a third search involving the reference lists of included articles, was utilized. Ten databases were searched. An additional 13 sources were searched for gray and/or unpublished literature. Included studies were assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute. Disagreements were resolved through discussion or with a third reviewer. A data extraction tool was used to extract data on interventions, populations, study designs and outcomes of significance to the review question. Statistical pooling was not possible, therefore a narrative synthesis was performed.

RESULTS

Thirty-one studies were included in the review (27 case reports and four case series). A total of 47 patients with Madura foot were analyzed. Twenty-five had eumycetoma, 21 actinomycetoma and one had both. Therapy involved varying dosages of sulfa drugs (co-trimoxazole and dapsone), amikacin and tetracyclines administered for the therapy of actinomycetoma with resolution of disease in all affected patients. The azole derivatives (itraconazole, ketoconazole, voriconazole, fluconazole and miconazole) as well as co-trimoxazole were the most commonly employed drugs for eumycetoma, with resolution of disease in 88% of included patients. Surgery was performed in a total of 21 patients with resolution of disease in all cases. The overall resolution rate following therapy was 95.7%.

CONCLUSION

Therapy for Madura foot is informed by case series and case reports which provide low level evidence for practice. Antimicrobials in conjunction with surgery lead to resolution of disease.

Clinico-radiological-pathological correlation in eumycetoma spectrum: Case series

Maduramycosis or mycetoma is one of the chronic granulomatous diseases commonly seen in tropical regions. Microbiological cultures and biopsy are carried out for the definitive diagnosis of the disease, but they are time-consuming methods. The present study aims to correlate clinical, radiological and pathological features in eumycetoma cases to emphasize the role of "dot in circle" sign leading to early imaging-based diagnosis. Imaging plays an important role in early diagnosis of mycetoma, which has therapeutic implications. "Dot in circle" sign is a recently described sign in mycetoma cases on ultrasound (USG) and magnetic resonance imaging (MRI). We diagnosed four cases of eumycetoma based on clinical and imaging features, which were confirmed with histopathology. The differential diagnosis, which may mimic this sign is also discussed. The "dot in circle" sign is seen on both ultrasound and MRI. This sign is highly specific for mycetomas. Knowledge of this sign can help in early diagnosis of mycetomas preventing misdiagnosis and further complications.

Mycetoma: An Update

Mycetoma is a localized chronic, suppurative, and deforming granulomatous infection seen in tropical and subtropical areas. It is a disorder of subcutaneous tissue, skin and bones, mainly of feet, characterized by a triad of localized swelling, underlying sinus tracts, and production of grains or granules. Etiological classification divides it into eumycetoma caused by fungus, and actinomycetoma caused by bacteria. Since the treatment of these two etiologies is entirely different, a definite diagnosis after histopathological and microbiological examination is mandatory, though difficult. Serological test exists but is not so reliable; however, molecular techniques to identify relevant antigens have shown promise. The disease is notoriously difficult to treat. Eumycetoma may be unresponsive to standard antifungal therapy. Actinomycetoma responds to antibiotic therapy, but prolonged treatment is necessary. This review focuses on the etiopathogenesis, clinical features, laboratory diagnosis, and treatment of mycetoma.

Estimated Burden of Serious Fungal Infections in Jamaica by Literature Review and Modelling

OBJECTIVE

Jamaica is one of the largest countries in the Caribbean with a population of 2 706 500. Prevalence of human immunodificency virus (HIV) in Jamaica is high, while that of tuberculosis (TB) is recorded to be low. In this study, we have estimated the burden of serious fungal infections and some other mycoses in Jamaica.

METHODS

All published papers reporting on rates of fungal infections in Jamaica and the Caribbean were identified through extensive search of the literature. We also extracted data from published papers on epidemiology and from the World Health Organization (WHO) TB Programme and UNAIDS. Chronic pulmonary aspergillosis (CPA), allergic bronchopulmonary aspergillosis (ABPA) and severe asthma with fungal sensitization (SAFS) rates were derived from asthma and TB rates. Where there were no available data on some mycoses, we used specific populations at risk and frequencies of fungal infection of each to estimate national prevalence.

RESULTS

Over 57 600 people in Jamaica probably suffer from serious fungal infections each year, most related to 'fungal asthma' (ABPA and SAFS), recurrent vulvovaginal candidiasis and AIDS-related opportunistic infections. Histoplasmosis is endemic in Jamaica, though only a few clinical cases are known. Pneumocystis pneumonia is frequent while cryptococcosis and aspergillosis are rarely recorded. Tinea capitis is common in children. Recurrent vulvovaginal candidiasis is very common (3154/100 000) and candidaemia occurs. Subcutaneous mycoses such as chromoblastomycosis and mycetoma also seem to be relatively common.

CONCLUSION

Local epidemiological studies are urgently required to validate or modify these estimates of serious fungal infections in Jamaica.

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.

WHO has recognized mycetoma as one of the neglected tropical diseases (NTDs) worldwide. Studies indicate infections from soil or possibly mediated by thorn pricks, but no detailed studies have investigated effects of soil type and Acacia distributions on mycetoma in Sudan. Here, we investigated risk factors associated with mycetoma infections in Sudan using ecological niche modeling (ENM), integrating mycetoma case records, Acacia records, and geospatial data summarizing soil, land-surface temperature, and greenness. ENMs calibrated in endemic districts were transferred across Sudan, and suggested that greatest risk was in a belt across central Sudan. Mycetoma infections occur under diverse environmental conditions; we found significant niche similarity between Acacia and mycetoma. Model predictions were amply corroborated by a preliminary assessment of a much larger mycetoma case-occurrence data base. Our results revealed contributions of different environmental factors to mycetoma risk, raised hypotheses of a causal mycetoma-Acacia association, and provide steps towards a robust predictive risk map for the disease in Sudan.

The Madura Foot

“Mycetoma” means a fungal tumor. Mycetoma is a chronic, granulomatous, subcutaneous tissue infection caused by both bacteria (actinomycetoma) and fungi (eumycetoma). This chronic infection was termed Madura foot and eventually mycetoma, owing to its etiology. Inoculation commonly follows minor trauma, predominantly to the foot and hence is seen more among the barefoot-walking populations, common among adult males aged 20 to 50 years. The hallmark triad of the disease includes tumefaction, fistulization of the abscess, and extrusion of colored grains. The color of these extruded grains in the active phase of the disease offers a clue to diagnosis. Radiology, ultrasonology, cytology, histology, immunodiagnosis, and culture are tools used in diagnosis. Recently, DNA sequencing has also been used successfully. Though both infections manifest with similar clinical findings, Actinomycetoma has a rapid course and can lead to amputation or death secondary to systemic spread. However, actinomycetomas are more responsive to antibiotics, whereas eumycetomas require surgical excision in addition to antifungals. Complications include secondary bacterial infections that can progress to full-blown bacteremia or septicemia, resulting in death. With extremely disfiguring sequelae, following the breakdown of the nodules and formation of discharging sinuses, it poses a therapeutic challenge.

Histological diagnosis of madura foot (mycetoma): a must for definitive treatment

Mycetoma, an uncommon chronic infection of skin and subcutaneous tissues in tropical countries is caused by true fungi (eumycetoma) or by filamentous bacteria (actinomycetoma). Since the treatment of these two etiologies is entirely different, a definite diagnosis after histopathological and microbiological examination is mandatory. We hereby present five cases of Madura foot.

Mycetoma or synovial sarcoma? A case report with review of the literature

Mycetoma, also commonly referred to as Madura foot, is statistically rare in the United States. However, it is endemic to other parts of the world. It is a pseudotumor characterized by a triad of tumefaction, draining sinuses, and grains. Two types exist, with each caused by different groups of organisms that require different treatment approaches. Therefore, the exact diagnosis and culture of the organism is vital to successful treatment outcomes. Synovial sarcoma, in contrast, is a malignancy much more commonly seen in the United States. It is characterized by a well-circumscribed, often palpable, mass that is usually well delineated on magnetic resonance imaging. It has characteristic histologic and genetic features that help distinguish it from other soft tissue masses. We present a case of a soft tissue mass diagnosed in the United States. The patient had several clinical and radiographic features of synovial sarcoma but the histologic outcome was mycetoma. The case is followed by a review of the published data.