What is the etiological agent for buruli ulcer which usually occur in the tropics?

Mycobacterium ulcerans is the causative organism for Buruli ulcer disease. It is the third most frequent mycobacterial pathogen, after M. tuberculosis and M. leprae. Children are most often affected. Infected individuals develop severe ulceration involving the skin and subcutaneous tissue that is often progressive unless treated effectively. Surgical excision and grafting are usually needed. Antimicrobial treatment is often unsuccessful. Ref: Sethi A. (2012). Chapter 184. Tuberculosis and Infections with Atypical Mycobacteria. In L.A. Goldsmith, S.I. Katz, B.A. Gilchrest, A.S. Paller, D.J. Leffell, N.A. Dallas (Eds), Fitzpatrick's Dermatology in General Medicine, 8e.