Growth inhibition of tubercle bacilli after pulsed exposures to combinations of antituberculous drugs.

All possible pairs of drugs chosen from the primary antituberculous agents including isoniazid, streptomycin, rifampin, and ethambutol were compatible and inhibited growth after administration to tubercle bacilli in a single 7 hr pulsed exposure. In general, combined drug effects could be best described as additive.