Eumycetoma — DTM&H MCQ

Correct answer: B — Grain microscopy and culture with imaging to define extent

The correct answer is B, grain microscopy and culture with imaging to define extent. A painless swollen foot (madura foot) with sinuses discharging black grains and bony involvement on x-ray is the classic presentation of mycetoma, and black grains are typically produced by eumycetoma agents such as Madurella mycetomatis. Definitive management depends on distinguishing eumycetoma from actinomycetoma, since treatment differs (antifungals plus surgery versus prolonged antibacterial regimens), and this distinction requires direct examination and culture of the grains rather than clinical appearance alone. Imaging (plain x-ray, ultrasound or MRI) is used alongside microbiology to stage bony and soft tissue extent, guiding surgical planning and monitoring treatment response. This combined microbiological and radiological work-up is the recommended diagnostic pathway in tropical medicine practice for suspected mycetoma. Why the other options are wrong: E. Blood film for malaria parasites: There is no fever or systemic illness suggesting malaria here, and a chronic localised swelling with draining sinuses and grains is not a feature of malaria. C. Serum dengue NS1 antigen: Dengue causes an acute febrile illness with viraemia detectable early in infection, not a chronic painless swelling with sinus tracts and grain discharge. D. Urine dipstick alone: This has no role in diagnosing a soft tissue and bone infection; it is used to screen for urinary abnormalities and would not identify the causative organism. A. Widal serology: Widal testing detects antibodies in suspected typhoid (enteric fever), which presents with fever and systemic symptoms, not a chronic foot mass with grain-discharging sinuses. Key point: Grain colour gives a clue but only grain microscopy and culture (with imaging to assess bone and soft tissue extent) can confirm eumycetoma versus actinomycetoma and guide correct treatment.

Reference: World Health Organization, Target product profile for a rapid test for diagnosis of mycetoma at primary health-care level, 2022, https://www.who.int/publications/i/item/9789240047075