FIG 6.
Ofloxacin resistance of vacuolar P. aeruginosa does not require cdrA or exopolysaccharide. (A to D) Percentage of human corneal epithelial cells containing intracellular P. aeruginosa at 12 h postinfection with (A) PAO1P, (B) PAO1PΔcdrA, (C) PAO1PΔEPS (ΔpelΔpslΔalgD), or D) PAO1PΔEPSΔcdrA. Total intracellular bacteria were detected using pGFParabinose (gray bars), and vacuolar cdrAon bacteria were detected using cdrA-GFP (red bars). Extracellular bacteria were killed after 3 h with amikacin (200 μg/mL) and with amikacin (200 μg/mL) and ofloxacin added at 3 h (4 to 64 μg/mL = 1 to 16× MIC). Intracellular bacteria persisted up to 16× MIC for the wild type and mutants, with a subset of each expressing cdrA. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 (one-way ANOVA with Dunnett’s multiple-comparison test versus untreated control). Data are shown as the mean ± SD of three biological replicates.