Short-course chemotherapy for isoniazid-resistant pulmonary tuberculosis

Standard short-course chemotherapy including isoniazid, rifampicin, pyrazinamide, and ethambutol has been the recommended treatment for tuberculosis in Taiwan since November 1990. The effectiveness of this treatment was evaluated retrospectively in 108 patients with isolates resistant to isoniazid alone and 115 patients with drug-susceptible pulmonary tuberculosis diagnosed and treated at the Taiwan Provincial Chronic Disease Control Bureau from November 1990 through December 1995. The success rate of treatment was 94.4% in patients with isoniazid-resistant Mycobacterium tuberculosis strains, which was not significantly different from the 97.4% rate in patients with susceptible strains. Of the patients treated successfully, no bacteriologic relapse was found in 97 patients with isoniazid-resistant strains or 103 patients with drug-susceptible strains 12 months after the end of chemotherapy. No significant advantage in treatment outcome was found in patients infected with isoniazid-resistant strains who received chemotherapy for more than 6 months (successful treatment rate, 95.0% vs 92.8%), but the failure rate was higher in patients with a previous history of antituberculosis therapy (17.6% vs 3.3%). We conclude that short-course chemotherapy is effective for isoniazid-resistant pulmonary tuberculosis and that there is no significant difference in treatment outcome between patients with or without isoniazid-resistant disease.