Figure 4. Intracellular growth kinetics of F. novicida mutants during hepatocyte infections.

BNL CL.2 cells were infected with wild-type F. novicida, deletion mutants (ΔiglC and ΔpdpA) and their respective complements. Bacteria were allowed to invade for 3 h after which extracellular bacteria were rapidly washed with PBS and killed with 100 µg mL⁻¹ of gentamicin for 1 h. Low concentrations of gentamicin (10 µg mL⁻¹) remained in the media (to inhibit extracellular bacteria) until experimental endpoint. Intracellular bacteria were then released by lysing host cells, diluted with TSBC, and plated for bacterial enumeration. Error bars, S.E.M. (n = 3).