An infection caused by the bacteria Mycobacterium kansasii. The bacteria can be found in water, dirt, and food. M. kansasii usually infects the lungs, but can also infect other organs and/or can spread throughout the body (disseminated). Most people with healthy immune systems are not affected by the bacteria. In people infected with HIV, M. kansasii infection that is outside of the lungs (extrapulmonary) or that has disseminated is an AIDS-defining condition.