Thrice-Weekly Clarithromycin-Containing Regimen for Treatment of Mycobacterium kansasii Lung Disease: Results of a Preliminary Study

We initiated a prospective trial of an intermittent clarithromycin-containing regimen for the treatment of patients with Mycobacterium kansasii lung disease. Eighteen patients (10 men and 8 women) with M. kansasii lung disease received a regimen consisting of 500-1000 mg of clarithromycin, 25 mg/kg ethambutol, and 600 mg of rifampin 3 times per week. The primary treatment end point was a 12-month period during which sputum cultures were sterile while the patient was receiving therapy. Four male patients were lost to follow-up, but all of the remaining patients successfully completed therapy without significant drug-related adverse events. The mean time (+/- standard deviation [SD]) to sputum conversion was 1.0+/-0.9 months, and the mean duration (+/-SD) of therapy was 13.4+/-0.9 months. No patient who successfully completed therapy had relapsed after a mean (+/-SD) of 46+/-8.0 months. Clarithromycin- and rifampin-containing regimens offer the possibility of effective short-course and intermittent treatment of M. kansasii lung disease.