Emergence of a unique group of necrotizing mycobacterial diseases

Although most diseases due to pathogenic mycobacteria are caused by Mycobac terium tuberculosis, several other mycobacterial diseases-caused by M. ulce rans (Buruli ulcer), M. marinum, and M. haemophilum-have begun to emerge. W e review the emergence of diseases caused by these three pathogens in the U nited States and around the world in the last decade. We examine the pathop hysiologic similarities of the diseases (all three cause necrotizing skin l esions) and common reservoirs of infection (stagnant or slow-flowing water) . Examination of the histologic and pathogenic characteristics of these myc obacteria suggests differences in the modes of transmission and pathogenesi s, though no singular mechanism for either characteristic has been definiti vely described for any of these mycobacteria.