Figure 2.

Bacterial phagocytosis assays revealed differences in invasiveness and intracellular survival among different K. pneumoniae strains. (A) Percentage of bacteria that were internalized after co-incubation of amoebae-Klebsiella for 1 h. (B) Total intracellular bacteria were titrated at the indicated times (T_x), and the results were expressed as the fraction respect the survival at time zero (T₀). In both (A,B), the symbols represent the mean of three independent experiments and the standard deviation. ^*p < 0.05, ^****p < 0.0001. (C) Live-cell imaging of D. discoideum cells (green) interacting with Klebsiella (red), representative of the experiments showed in (A,B). Bright field and fluorescence images were blended in order to better appreciate the boundaries of the amoeba cells. At time 24 h, two pictures of amoebae infected with Kp 700603 are shown in order to illustrate that both extracellular (upper picture) and intracellular bacteria (lower picture) could be observed. Scale bar, 10 μm.