Figure 3.

The M. tuberculosis survives in the bone marrow (BM) after anti-tuberculosis therapy. Mice were infected with 82 ± 52 M. tuberculosis Erdman bacilli by aerosol. Starting at day 28 of M. tuberculosis infection, mice received rifampicin and isoniazid continuously in the drinking water. At the indicated time points, viable M. tuberculosis colony forming unit (CFU) were recovered from lungs, spleens, and BM. Data are from two independent experiments each with four to six mice per time point (n = 8 to 12 mice) and shown as the means ± SEM. The last time points that M. tuberculosis could be recovered from the spleens and lungs were after 65 and 93 days, respectively, of continuous antibiotic therapy (days 121 and 220 after infection, respectively). In contrast, viable M. tuberculosis CFUs could be recovered from BM at all of the time points tested. Control CFU yields for mice receiving sterile water (instead of antibiotics) are depicted in Figure 1 (experiments were performed concomitantly).