Figure 5. Growing bacteria are enriched for antibiotic tolerance.

(A and B) J774A.1 macrophages were infected with Mm and were treated with 100 nM dexamethasone at t=0. Macrophages were lysed at 96 hpi to release bacteria. (A) Total CFU at time of release. (B) Percent survival of released bacteria upon 48 hours exposure to 174 µM INH, 1.21 µM RIF, or left untreated.

(C) J774A.1 macrophages were infected with Mm/pBP10 and total and Kan^R CFU enumerated at 48 and 96 hpi. The cumulative bacterial burden (CBB) was calculated as described in the Supplemental Experimental Procedures. (D) Mm/pBP10 grown intracellularly for 96 hours (described in (C)) were released by macrophage lysis and then treated for an additional 48 hours with 174 µM INH, 1.21 µM RIF, 7.48 µM MOX, or left untreated, prior to enumeration of total and Kan^R CFU. Kan^S CFU were calculated as the total CFU minus the mean Kan^R CFU. In all panels, error bars represent SEM, and P values were determined using Student’s t-test.