Etiology

• TB is an infectious disease caused by bacteria of the Mycobacterium tuberculosis complex, of which M. tuberculosis is the most common and important agent causing human disease.
• Similar disease occasionally results from the closely related mycobacteria, M. bovis, M. africanum, and M. microti.
• In 1882, Robert Koch demonstrated that the tubercle bacillus was the true cause of TB, a discovery for which he received the Nobel Prize in 1905.