A comparative study of tuberculous and other mycobacterial infections and their associations with malignancy

We reviewed 162 cases of bacteriologically proved mycobacterial disease. Nontuberculous acid-fast bacilli were responsible for 27 per cent of the infections, a higher frequency than has previously been reported, and Mycobacterium kansasii and Mycobacterium avium-intracellulare were isolated with equal frequency. This indicates that Mycobacterium avium-intracellulare may be a significant agent of disease in the Midwest as well as the Southeast. There are no useful clinical, radiographic, or laboratory features to distinguish between tuberculous and other mycobacterial infections. Mycobacteria act as opportunistic pathogens in persons with malignant diseases. The attack rate was 607 of 100,000 persons verus 95 of 100,000 persons in our general hospital population. Mycobacterium tuberculosis and the nontuberculous mycobacteria were of equal virulence in this regard.