Evaluation of the 3-drug combination, Rifater, versus 4-drug therapy in the ambulatory treatment of tuberculosis in Cape Town.

The subjective impression among clinicians that the use of Rifater was causing delayed sputum conversion and increased drug resistance was tested in a prospective study. Adults in the Cape Town municipal area with a first episode of pulmonary tuberculosis were treated either with Rifater or a regimen consisting of isoniazid, rifampicin, pyrazinamide and ethambutol. All patients who took the treatment as prescribed (67 Rifater, 39 the 4-drug regimen) converted to a negative sputum culture by the time 90 doses had been taken. The rates of inadequate compliance and of side-effects were similar in the two groups. Drug sensitivity testing of bacteria cultured from pre-treatment sputum specimens revealed an overall primary resistance rate of 4.84% in the population studied, sufficiently low to preclude any necessity for routine pre-treatment drug sensitivity testing.