BALB/c mice were infected intranasally with 103 H37Rv strain of Mtb, and animals were orally treated for 4 weeks following 1 or 4 weeks of infection in acute (A) and established (B) efficacy models, respectively. Efficacy of test compounds was measured by Δlog CFUs compared to untreated controls independently for lung and spleen. Statistical evaluation was done using one way ANOVA and the data was analyzed using Tukey's multiple comparison test. Statistical significance was accepted with P values <0.05. All bars labeled with the same letter of the alphabet do not differ significantly. INH, isoniazid; RIF, rifampicin and EMB, Ethambutol.