A 30 year old farmer from the sub-Himalayan region presents with multiple leg ulcers. The most likely causative agent is:

Sporothrix schenckii is a thermally dimorphic fungus that lives on vegetation. The conidia or hyphal fragments of S schenckii are introduced into the skin by trauma. Patients frequently recall a history of trauma associated with outdoor activities and plants. The initial lesion is usually located on the extremities but can be found anywhere (children often present with facial lesions). About 75% of cases are lymphocutaneous; ie, the initial lesion develops as a granulomatous nodule that may progress to form a necrotic or ulcerative lesion. Meanwhile, the draining lymphatics become thickened and cord-like. Multiple subcutaneous nodules and abscesses occur along the lymphatics. Oral itraconazole or another of the azoles is the treatment of choice. For systemic disease, amphotericin B is given. Ref: Brooks G.F., Carroll K.C., Butel J.S., Morse S.A., Mietzneron T.A. (2010). Chapter 45. Medical Mycology. In G.F. Brooks, K.C. Carroll, J.S. Butel, S.A. Morse, T.A. Mietzneron (Eds), Jawetz, Melnick, & Adelberg's Medical Microbiology, 25e.