Overnight TSB-C broth cultures of LVS (A-C) and Schu S4 strains (D-F) were pelleted, resuspended in PBS, and added to mouse macrophages (A,D), human macrophages (B,E), or A549 cells (C,F) at a MOI of 500. Bacteria were incubated with cells for two hours and subsequently subjected to gentamicin treatment as described in the Materials and Methods. At the indicated time points, cells were lysed and CFU enumerated. Data are expressed as the mean ± SEM of at least two independent experiments. No significant difference (p < 0.05) was detected with any cell type or time point by one-way ANOVA followed by a Bonferroni multiple comparison correction.