FIG 4 .

ExoS contributes to decreased bacterial uptake by phagocytes in vitro. (A) J774 macrophage-like cells were infected for 3 h with strain PA99S or PA99null and stained differentially to distinguish intracellular bacteria (red; red arrow) from extracellular bacteria (red and green; green arrow). DAPI, 4′,6′-diamidino-2-phenylindole. (B) Average numbers of intracellular and extracellular bacteria per phagocyte were counted (300 phagocytes pooled from four separate experiments). Error bars represent standard errors of the means between four separate experiments.