A patient presented with a swelling in his right foot with multiple discharging sinuses that contained brown granules. The lesion did not respond to antibiotic medications. Which of the following is the causative agent?

The history of multiple discharging sinuses that contained brown granules and the non-responsiveness to the antibiotics are suggestive of Eumycetoma. The causative agent of this is Madurella mycetomatis. Actinomadura and Nocardia cause actinomycetoma which would respond to antibiotics. Mycetoma is of two types: Eumycetoma Actinomycetoma Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition