PULMONARY INFECTIONS CAUSED BY LESS FREQUENTLY ENCOUNTERED SLOW-GROWING ENVIRONMENTAL MYCOBACTERIA

Pulmonary mycobacteriosis is usually caused by Mycobacterium tuberculo sis or Mycobacterium avium complex. There are, however, other slow-gro wing mycobacteria that can cause pulmonary infection. Mycobacterium ka nsasii, Mycobacterium malmoense, Mycobacterium xenopi, Mycobacterium s zulgai and Mycobacterium simiae typically infect middle-aged to elderl y persons with preexisting lung disease. Differentiation of infection with these five mycobacteria from infection with Mycobacterium tubercu losis, by culture and determination of the antimicrobial susceptibilit y pattern of the organism are important for several reasons. All five organisms are found in water and soil. They probably infect humans fro m environmental habitats; human-to-human spread of infection is though t not to occur, Furthermore, isolation of the organisms in culture may represent contamination of the specimen or colonization of the patien t, and not necessarily an infection. Finally, although the antitubercu losis - drugs isoniazid, ethambutol, rifampin and streptomycin - have been used for treatment of infection with these five organisms, there are often differences between the antimycobacterial susceptibility pat terns of Mycobacterium tuberculosis and those of the nontuberculous my cobacteria. Thus, the optimal choice of drug therapy may differ from t hat used for tuberculosis.