FIG 1.

Ceftazidime and IFN-γ induce synergistic killing of intracellular bacteria in macrophages. Adherent RAW 264.7 cells (A) or primary bone marrow macrophages from C57BL/6 mice (B), BALB/c mice (C), or ICR mice (D) were infected with B. thailandensis and treated with ceftazidime (10 μg/ml for RAW 264.7 cells, 3 μg/ml for bone marrow macrophages), IFN-γ (10 ng/ml), or the combination of ceftazidime and IFN-γ for 18 h. Intracellular bacteria were then enumerated by plating macrophage lysates. Synergistic interactions between ceftazidime and IFN-γ were determined by two-way ANOVA (*, P < 0.01; **, P < 0.001; ***, P < 0.0001). Graphs are representative of data from two independent experiments with treatment groups run in triplicate.