FIGURE 3.

Measurement of trans-epithelial resistance (TER), CFU and PFU at 24 h of Calu-3 cells infected with P. aeruginosa PAO1 and treated with ϕ54. (A) Phages alone do not affect TER and remain infective for 24 h. Cell integrity is maintained by ciprofloxacin (CIP) treatment (4 mg/ml) or addition of phage at an initial inoculum of 10² to 10⁶ PFU/well. (B) Treatment with CIP or phage reduces PAO1 counts after 24 h. (C) In the absence of PAO1, phage titers remain constant during 24 h. In the presence of PAO1, phage replicate to the same titer independent of the initial inoculum. Values represent median and range of three independently performed experiments. Differences in TER between the conditions were assessed using a one-way ANOVA; *p < 0.05, **p < 0.01, ***p < 0.005.