- Chronic progressive granulomatous implantation infection of the skin and subcutaneous tissue, usually affecting a single extremity
- Caused by either fungi or fungal-like bacteria
Background
Microbiology
- Can be caused either by fungi or filamentous aerobic bacteria
- For a comprehensive review, refer to 1
- Fungal species (eumycotic mycetoma):
- Dark grains:
- Pale/white grains:
- Pseudallescheria boydii (most common) (Scedosporium)
- Acremonium kiliense
- Aspergillus flavus, Aspergillus nidulans, Aspergillus hollandicus
- Aerobic bacteria (actinomycotic mycetoma):
- Nocardia brasiliensis
- Actinomadura madurae
- Streptomyces somaliensis
- Actinomadura pelletieri (grains are red to pink)
Epidemiology
- Present worldwide between 15ºS and 30ºN
- Within Latin America, Mexico has the highest incidence
- Also relatively high incidence in Chad, Ethiopia, India, Mauritania, Senegal, Somalia, Sudan, Yemen, and Venezuela
- More common in poorer, rural communities
Clinical Manifestations
- Chronic implantation fungal infection characterized by swelling and draining sinuses
- Can involve deeper tissues such as muscle or bone (in contrast to chromoblastomycosis)
- Clinical triad:
- Localized swelling
- Underlying sinus tract
- Grains and granules (“sulfur granules”) within the sinus tracts
- May spread via lymphatics in a sporotrichoid pattern
Comparison of eumycetoma and actinomycetoma
Eumycetoma | Actinomycetoma | |
---|---|---|
Location | Africa and India | Latin America |
Patients | 20 to 40 years old | 40 to 50 years old |
Distribution | Predominantly feet | |
Progression | Less aggressive | More aggressive |
Clinical features | Few fistulae with proliferative sinuses, late bone involvement with large bone cavities | Many fistulae with flat sinuses, early bone involvement with small bone cavities |
Differential Diagnosis
- Spororichosis
- Yaws
- Non-tuberculous mycobacteria
- Tuberculosis
- Osteomyelitis
- Syphilitic osteitis
- Neoplasms, including Kaposi sarcoma, fibroma, neurofibroma, malignant melanoma, fibrolipoma, osteosarcoma, rhabdomyosarcoma, osteogenic sarcoma
- Other non-infectious causes, including foreign body granulomatous reaction and bone cysts
Diagnosis
- Specimen collection
- Send granules in sterile container
- Can do skin scraping in areas of moist or broken skin
- Skin biopsy
- Histology/microscopy
- Gram stain a crushed granule for bacteria
- Culture
- Set up cultures for bacterial and fungal culture
Management
- May need imaging to assess severity and help plan management2
- Ultrasound is the most commonly used
- CT and MRI may also be helpful
- Actinomycetoma can be managed medically
- Standard treatment is trimethoprim-sulfamethoxazole 48 mg/kg per day for 5 weeks followed by amikacin 15 mg/kg daily divided q12h for 3 weeks, followed by a 2 week interval, then repeated until cured (usually four cycles)
- May substitute amoxicillin-clavulanic acid for the trimethoprim-sulfamethoxazole
- Rescue therapies substitute in a carbapenem for the trimethoprim-sulfamethoxazole
- Can also try combination trimethroprim-sulfamethoxazole plus either dapsone or streptomycin
- Standard treatment is trimethoprim-sulfamethoxazole 48 mg/kg per day for 5 weeks followed by amikacin 15 mg/kg daily divided q12h for 3 weeks, followed by a 2 week interval, then repeated until cured (usually four cycles)
- Eumycetoma is more difficult to treat, and usually requires medical management for months to a year, followed by wide local excision of the lesions
- Antifungals should be targetted to the causative organism, or empirically against Madurella mycetomatis
- Recommended empiric treatment is with itraconazole 200 to 400 mg/day for 6 to 9 months
- Can also try ketoconazole 400 to 800 mg/day for 9 to 12 months or terbinafine
- Treatment shrinks but does not necessarily cure the lesions
Further Reading
- Mycetoma: a unique neglected tropical disease. Lancet Infect Dis. 2016;16(1):100-112. doi: 10.1016/S1473-3099(15)00359-X
References
- ^ Wendy W. J. van de Sande, Ahmed H. Fahal. Graeme N. Forrest. An updated list of eumycetoma causative agents and their differences in grain formation and treatment response. Clinical Microbiology Reviews. 2024;37(2). doi:10.1128/cmr.00034-23.
- ^ Wendy W. J. van de Sande, Ahmed H. Fahal, Michael Goodfellow, El Sheikh Mahgoub, Oliverio Welsh, Ed E. Zijlstra. Todd Reynolds. Merits and Pitfalls of Currently Used Diagnostic Tools in Mycetoma. PLoS Neglected Tropical Diseases. 2014;8(7):e2918. doi:10.1371/journal.pntd.0002918.