Assessment of CFU counts in the organs before, during, and after treatment with combination regimens. Treatment was administered for 4 weeks (A and B) or 8 weeks (C and D), and CFU counts were determined in mouse lungs (A and C) and spleens (B and D) at the indicated time points. Data represent the means (4 to 6 mice per group per time point), and the error bars represent the standard deviations. CFU counts are presented in Tables S1 and S2 in the supplemental material. R, rifampin administered at 10 mg/kg; H, isoniazid administered at 10 mg/kg; Z, pyrazinamide administered at 150 mg/kg; E, ethambutol administered at 100 mg/kg; C, clofazimine administered at 25 mg/kg. Asterisks represent statistically significant differences in CFU counts posttreatment compared to those at the time of treatment cessation (*, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001).