This patient has pulmonary tuberculosis and is completing a 2-month initial phase of treatment with the three-drug regimen of rifampin, isoniazid, and ethambutol and will require a 7-month continuation phase consisting of isoniazid and rifampin. Although most patients with active tuberculosis are treated with a four-drug regimen, usually consisting of rifampin, isoniazid, ethambutol, and pyrazinamide, pyrazinamide is contraindicated for use in patients with active gout and should be used with caution in chronic gout because it inhibits renal tubular excretion of uric acid. In most patients, a continuation phase of 4 months of isoniazid and rifampin is recommended for treatment of drug-susceptible tuberculosis. However, a 7-month continuation phase of isoniazid and rifampin is recommended in patients who do not receive pyrazinamide during the initial phase, in patients receiving once-weekly isoniazid and rifapentine whose sputum cultures are still positive at the end of the initial treatment phase, and in patients with cavitary pulmonary tuberculosis whose sputum cultures are positive at end of the initial phase of treatment. Because this patient did not receive pyrazinamide as part of his initial drug regimen, he should be treated with a 7-month continuation phase.

In the absence of drug resistance, 6 to 9 months of total treatment is sufficient. Longer courses extending beyond 9 months are reserved for multidrug-resistant tuberculosis.