Uptake of P. aeruginosa by human macrophages. Strains were incubated with 1.5 × 105 cells/ml macrophages for 1 h at an MOI of 10. Subsequently, extracellular and attached bacteria were killed by treatment with gentamicin, and macrophages were lysed with Triton X-100 and lysates plated to enumerate viable intracellular bacteria. Results are expressed as the percentage of intracellular bacteria that were recovered relative to the PA14 WT. The box plots (median, thick line in the box) represent the mean of 3 independent biological repeats, each assayed minimum in duplicate (n = ≥6). *** indicates a statistically significant difference (p < 0.001), between the typA and pscC mutant and PA14 WT as determined by Whitney Mann test.