A 40-year-old agricultural worker from Tamil Nadu has a slowly enlarging, firm, painless swelling of the right foot over three years, studded with draining sinus tracts that discharge small black grains. The most likely causative organism is:
- A Nocardia brasiliensis
- B Madurella mycetomatis ✓
- C Streptomyces somaliensis
- D Actinomadura madurae
Correct answer: B. Madurella mycetomatis
Explanation
Black grain eumycetoma in India is classically caused by Madurella mycetomatis, a true fungus. Nocardia brasiliensis and Actinomadura madurae produce white to yellow grains, and Streptomyces somaliensis produces yellow to brown grains, so grain colour separates them. Black grains point to a fungal agent such as Madurella or Exophiala.
Reference: Rook's Textbook of Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.