What is the treatment for a patient, likely from a tropical or subtropical region with a history of outdoor activities, presenting with mycetoma grains on the bottom of their feet?

Treatment of Mycetoma on the Feet

Mycetoma requires immediate differentiation between actinomycetoma (bacterial) and eumycetoma (fungal) because treatment differs fundamentally, with actinomycetoma having excellent cure rates with antibiotics while eumycetoma responds poorly to antifungals and often requires surgery. 1, 2

Immediate Diagnostic Steps

Before initiating treatment, you must obtain tissue specimens to identify the causative organism:

• Perform surgical debridement and obtain deep tissue specimens (not superficial swabs) for culture, microscopy, and histopathology 3
• Express and examine grains from discharging sinuses—grain color and consistency help distinguish bacterial from fungal etiology 1, 2
• Send specimens for both bacterial and fungal culture, as this determines the entire treatment approach 3, 4
• Consider molecular sequencing (PCR) if cultures are negative, as this provides rapid and accurate diagnosis 1
• Obtain imaging (radiography, ultrasound, or MRI) to assess bone involvement and extent of disease 1, 4

Treatment Based on Etiology

For Actinomycetoma (Bacterial)

First-line treatment combines trimethoprim-sulfamethoxazole (co-trimoxazole) 160/800 mg daily with amikacin 15 mg/kg body weight per day, which achieves clinical cure in over 50% of cases with low recurrence rates 2, 5

Alternative regimen for Actinomadura madurae:

• Doxycycline as prolonged chemotherapy (specific dosing not standardized but requires months of treatment) combined with surgical debridement 3
• Treatment duration typically extends 6-12 months even after clinical resolution to prevent recurrence 2, 4

For Eumycetoma (Fungal)

Itraconazole 200 mg twice daily is the gold standard for eumycetoma, though response is often poor and treatment may require years 2, 5

• Expect high recurrence rates (20-90%) even with optimal medical therapy 5
• Surgical excision of affected tissue is often necessary as adjunct to antifungal therapy, particularly for extensive disease 2, 5
• Amputation may be required for advanced cases with bone involvement and treatment failure 5

Critical Management Principles

Early surgical debridement is mandatory for all mycetoma cases regardless of etiology, both for diagnosis and to reduce organism burden 3, 4

Treatment must be prolonged—measured in months to years rather than weeks—to achieve cure and prevent recurrence 2, 4

Monitor closely for bone involvement, as this significantly worsens prognosis and may necessitate more aggressive surgical intervention 1, 4

Prevention Counseling

Advise wearing protective footwear and garments, especially during outdoor activities in rural areas, as mycetoma results from traumatic inoculation of organisms through minor skin injuries 1, 2

Common Pitfalls

• Do not treat empirically without tissue diagnosis—the distinction between actinomycetoma and eumycetoma is fundamental, as bacterial forms respond well to antibiotics while fungal forms have poor outcomes 2, 4
• Do not rely on superficial swabs—deep tissue specimens from debrided areas are essential for accurate diagnosis 3
• Do not stop treatment prematurely—recurrence rates are extremely high if treatment duration is inadequate 2, 5
• Do not delay surgical consultation—extensive disease may require amputation, and early aggressive management improves outcomes 5