Table 1.
Strains used in this study.
Fig 1.
Mannitol does not sensitize non-mucoid, laboratory strain P. aeruginosa PA14 to tobramycin.
A. Mannitol is minimally cytotoxic to CFBE cells. Normalized cytotoxicity as measured by fraction of LDH release. Cytotoxicity was measured after 24 hours of treatment with 0, 40 or 60 mM mannitol as indicated. Cells lysed with Triton X-100 served as a control to determine total lysis. Columns indicate mean of at least three biological replicates, error bars indicate standard deviation (S.D.). **, P<0.01, comparison of indicated sample to total lysis control by ordinary one-way ANOVA with Tukey’s post test for multiple comparisons. B. Viability of P. aeruginosa PA14 grown as a biofilm on CFBE cells after treatment 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<0.001 by ordinary one-way ANOVA with Tukey’s post test for multiple comparisons. There is no significant difference between P. aeruginosa PA14 treated with tobramycin +/- mannitol.
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.