Although recognized for a long time, it was not until recently that serious consideration was given to mycobacteria other than mammalian tubercle bacilli as agents of human disease. These so-called "atypical" mycobacteria now account for approximately 1 to 5% of newly recognized mycobacterial infections.
Chronic pulmonary disease resembling ordinary tuberculosis is probably the most common. M. kansasii (slow growing, photochromogenic) is the usual pathogen except in the Southeastern states, where most of these infections are associated with the avian-like, nonpigmented "Battey bacilli." Orange-pigmented, smooth strains (scotochromogens), and rapidly growing strains like M. fortuitum have occasionally been implicated.
Subacute lymphadenitis in