Infection with Mycobacterium lepromatosis.

Microbiologically speaking, the ancient scourge of leprosy has a new face. Considered a curse for millennia, the causative agent, Mycobacterium leprae, was first described by Armauer Hansen in 1874. This inaugurated the field of medical microbiology, preceding the discovery of Mycobacterium tuberculosis But M. leprae is not cultivable, a fact that has greatly hindered many of the basic studies that enabled rapid progress in understanding other infectious diseases. Sequencing of the full M. leprae genome ushered in a new era in the microbiology of this disease, and it was not long before molecular studies identified a genetically similar organism associated with leprosy, dubbed "Mycobacterium lepromatosis".