M. lepromatosis is an acid-fast bacillus (AFB) which causes diffuse lepromatous leprosy (DLL). DLL is mainly found in Mexico and the Caribbean. DLL is a severe form of leprosy which manifests through nerve invasion and extensive skin ulcerations due to massive AFB burden in internal organs.M. lepromatosis, like M. leprae, has not been cultured in the laboratory because they both lack genes necessary to grow outside of their hosts. These genes are believed by scientists to have been lost through reductive evolution.
^ abcdNair, R. Geetha; Li, Wei; Spencer, John S.; May, Gregory S.; Schoberle, Taylor; Sizer, Kurt C.; Seo, Yiel-Hea; Han, Xiang Y. (2008). "A New Mycobacterium Species Causing Diffuse Lepromatous Leprosy". American Journal of Clinical Pathology130 (6): 856–64. doi:10.1309/AJCPP72FJZZRRVMM. PMID19019760. Lay summary.