Antituberculous agents.

Antituberculous agents have radically improved the prognosis of patients with active tuberculosis. Generally, 6-month and 9-month regimens have been successful, and surgical therapy is rarely necessary. Extrapulmonary tuberculosis should be managed with the drug regimens outlined for pulmonary tuberculosis. The major cause of therapeutic failure is poor compliance of the patient in taking the medication regularly. The second major cause of treatment failure is resistance of tubercle bacilli to the antimicrobial agents used. When treatment failure is apparent, careful reassessment by physicians experienced in the treatment of tuberculosis is indicated. A single drug should never be added to a failing regimen. For prophylaxis, isoniazid, given for 6 to 12 months, is effective in most cases.