Mannitol Does Not Enhance Tobramycin Killing of Pseudomonas aeruginosa in a Cystic Fibrosis Model System of Biofilm Formation
Fig 2
Mannitol does not sensitize P. aeruginosa clinical isolates grown as biofilms on CF airway cells to tobramycin.
A. Viability of P. aeruginosa clinical isolates grown as biofilms on CFBE cells and treated with 0 μg/mL tobramycin (open bars), 8 μg/mL tobramycin (hatched bars), 0 mM mannitol (white bars), 60 mM mannitol (gray bars) or co-treatment with 8 μg/mL tobramycin and 60 mM mannitol, as indicated. Columns indicate mean of at least three biological replicates, error bars indicate S.D. **, P<0.01 by ordinary one-way ANOVA with Tukey’s post test for multiple comparisons. B. The viability of strains P. aeruginosa PAO1 (left) and FRD1 (right) as biofilms on CFBE cells and treated with 0 μg/mL tobramycin (open bars), 8 μg/mL tobramycin (hatched bars), 0 mM mannitol (white bars), 60 mM mannitol (gray bars) or co-treatment with 8 μg/mL tobramycin and 60 mM mannitol, as indicated. **, P<0.01 or ***, P<0.001 by ordinary one-way ANOVA with Tukey’s post test for multiple comparisons. ns, not significant compared to tobramycin treatment in the absence of mannitol. C. The viability of strain P. aeruginosa PAO1 as a biofilm on plastic and treated with 0 μg/mL tobramycin (open bars), 80 μg/mL tobramycin (hatched bars), 0 mM mannitol (white bars), 60 mM mannitol (gray bars) or co-treatment with 80 μg/mL tobramycin and 60 mM mannitol, as indicated. *, P<0.05 compared to treatment with 80 μg/mL tobramycin with no mannitol. **, P<0.01 or ***, P<0.001 by ordinary one-way ANOVA with Tukey’s post test for multiple comparisons.