FIG 7.

Ceftazidime controls primarily extracellular bacterial burden. (A) RAW 264.7 macrophages were infected with B. thailandensis and treated for 24 h with IFN-γ (10 ng/ml), ceftazidime (10 μg/ml), or the combination of IFN-γ and ceftazidime. Extracellular bacterial burden was assessed at 0, 6, 10, and 24 h posttreatment by plating serial dilutions of well supernatants. Significant differences were assessed at all time points by two-way repeated-measures ANOVA and compared to the untreated control (*, P < 0.05; ***, P < 0.001). (B and C) B. thailandensis was treated with ceftazidime (10 μg/ml), IFN-γ (10 ng/ml), or the combination of both treatments for 18 h in the absence of macrophages. Surviving bacteria were enumerated by plating dilutions of remaining bacteria in wells after 18 h of treatments. Significant differences were assessed by one-way ANOVA, a > b > c > d (P < 0.0001). All graphs are representative of results from two independent experiments with treatment groups run in triplicate.