Short-course chemotherapy for mycobacteriosis kansasii?

The success of short-course chemotherapy for tuberculosis, the similarity between Mycobacterium tuberculosis and M. kansasii and the effectiveness of rifampin against the latter organism prompted a comparison of the diseases due to these organisms to assess the feasibility of a prospective trial of short-course chemotherapy in patients with mycobacteriosis kansasii. The two groups of patients were matched for age, sex and time of diagnosis. The patients with mycobacteriosis kansasii more frequently had underlying obstructive pulmonary disease. The clinical course of mycobacteriosis kansasii was more indolent, with a slower rate of improvement according to the chest x-ray films and a longer time before sputum smears and cultures became negative. M. kansasii was significantly more resistant to all the antibiotics, including rifampin. Although these differences from tuberculosis suggest that an equally short course of therapy may not be effective for patients with mycobacteriosis kansasii, the outcome was good in compliant patients who were given the three most effective major drugs for 12 months after the sputum smears and cultures had become negative. Therefore, a trial of modified short-course chemotherapy is recommended for patients with mycobacteriosis kansasii.