Mycetoma Diagnosis and Causative Agents

Definition
- Mycetoma is a chronic, locally progressive, destructive, suppurative, and granulomatous disease.
- It begins in the subcutaneous tissue usually of the foot.
- This involves subcutaneous tissue, fascia, and bone.
- It is characterized by the tumefaction, draining sinuses, and the presence of granules.
Pathology
- Mycetoma is caused by two types of microorganisms:
- Bacteria are aerobic actinomycetes which are the cause of Mycetoma called Actinomycetoma, in more than 50% of the cases.
- The organism in this group are:
- Nocardia brasiliensis.
- Actinomadura pelletieri.
- Actinomadura madurae.
- Streptomyces somaliensis.
- Actinomyces are:
- Actinomyces israelli.
- Actinomyces bovis.
- The organism in this group are:
- Fungal infection causes in the other 50% of the cases.
- This is called Eumycetoma, and also known as maduromycosis, and caused by true fungus.
- There are at least 23 types of filamentous fungi that cause Mycetoma. An important one is:
- Pseudallescheria boydii (There are yellow granules).
- Madurella mycetomatis (There are big black granules).
- Medurella grisea.
- There are at least 23 types of filamentous fungi that cause Mycetoma. An important one is:
- This is called Eumycetoma, and also known as maduromycosis, and caused by true fungus.
Presentation
- Mostly there is the involvement of the feet and less common hands and other sites.
- This is chronic, suppurative, granulomatous inflammation which can involve subcutaneous tissue, fascia, and bone.
- The etiological agents gain entry into the body through the foot from the soil which may be due to trauma.
- When there is the involvement of the foot, where it is swollen and discolored and numerous draining sinuses.
- This disease is characterized by tumor formation and draining the abscess.
- There is the presence of granules or grains. in the pus.
- These granules have different colors, white, black, yellow, and brown depending upon the causative agents.
- Mycotic mycetoma is common in men than in women.
- Mycotic mycetoma is usually due to an injury to the foot.
Pathogenesis
- When fungi are implanted in the subcutaneous tissue following the trauma.
- There is a destructive granulomatous lesion that drains through multiple sites.
- There is local spread but no dissemination.
Laboratory Diagnosis
- Collect the granules from the lesion.
- Then wash the granules by the saline, then crush and spread on the slide.
- Also, take the culture of the material. Culture is done on the Sabouraud’s medium for fungus.
- Prepared slides are stained with Gram’s stain :
- The filaments are less than or equal to 1.0 micrometer in diameter, these are diagnostic of aerobic actinomycetes and called actinomycetoma.
- If the filaments are 2 to 5 micrometers and hyphal in shape is diagnostic of fungal infection is called eumycetoma.
- These granules can also be seen by KOH 10% solution.
Treatment
- The prognosis of Eumycetoma is poor.
- These patients undergo surgical debridement, oral Itraconazole 200 mg twice a day for a prolonged period of time and response is only 70%.
- These patients may be given combination therapy.
- Mostly these are treated by surgery.
- Chemotherapy is not effective and given for a prolonged period of time.