Fluorescence microscopy images of BMDMs infected with (A–C) wild type Schu S4-GFP or (D–F) intracellular growth defective mutant △FTT_0924-GFP, permeabilized with saponin and treated with propidium iodide (PI). (A,D) GFP positive bacteria (green), (B,E) PI positive bacteria (white), (C,F) merged images. (G) Proportion of PI positive (dead) intracellular wild type (WT) and growth deficient mutant bacteria (△FTT_0924). The data were analyzed from n = 100 macrophages per strain from 3 independent experiments. (Mean +/- SD) (***P<0.001).