Figure 6.

Klebsiella pneumoniae fimK promotes serum resistance, capsule production, and resistance to phagocytosis. A, In serum resistance assays, bacteria were incubated with pooled human active (solid bars) or inactivated (open bars) serum for 3 hours. Bacterial survival is expressed as a percentage of input colony-forming units (CFU). B, Capsule extraction and quantification was performed on bacteria grown with (open bars) and without (solid bars) the capsule inhibitor sodium (Na) salicylate. C, Mice were intratracheally inoculated with fluorescein isothiocyanate (FITC)–labeled bacteria, and bronchoalveolar lavage was performed at 3 hours after infection. The percentage of macrophages expressing FITC was determined by flow cytometry after infection with TOP52 (circles) or TOP52ΔfimK (triangles). All data are combined from 2 independent experiments and shown as mean or mean ± standard error of the mean (**P < .01 and ***P < .001, by the Mann–Whitney U test).