Fig 1.
(a) Growth pattern and (b) biofilm formation of P. aeruginosa strains used in study.
Table 1.
Antibiotic susceptibility pattern of P. aeruginosa strains used in the study.
Fig 2.
Checkerboard showing effect of antibiotic-quercetin combinations against P. aeruginosa strains.
Pink color represents growth inhibition (additive/MIC), cream color indicates the synergistic effect with growth inhibition. Green shows no reduction in the growth (no effect) based on the visible turbidity. The P. aeruginosa strains were treated with fractional concentration of antibiotic with quercetin in 96-well MHB for 24 h. The growth based on visible turbidity was used for interpreting the results.
Fig 3.
Combenefit mapped surface HSA plot.
The data based on the OD600 values obtained for antibiotic-quercetin combination from the 24 h incubation was used to generate this heat map. Light blue to dark blue shows increased reduction (synergy) while yellow-red shows no reduction (non-synergy).
Fig 4.
Time kill assay data showing the growth pattern of P. aeruginosa strains treated with antibiotic-quercetin combinations at lowest FICi for 24 h.
(a-e) represents five different strains. (f) shows the CFU/mL data obtained from the cultures of 24 h incubation by serial dilution plate method.
Fig 5.
Effect of antibiotic-quercetin combinations at lowest FICi on biofilm.
Percentage effective combination of antibiotics with quercetin showing reduction in the biofilm. (a) Percentage of inhibition of biofilm formation (b) Biofilm cell viability of the treated pre-formed biofilms. (a) The bacteria were grown in 96-well plate in presence of antibiotic-quercetin combination and biofilm intensity was assessed by crystal violet staining. (b) Biofilm viability was tested after treating the pre-formed biofilms in 96-well plate with antibiotic-quercetin combinations.
Fig 6.
Biofilm viability as visualized by live/dead staining for P. aeruginosa (YU-V10, YU-V28, YU-V11, YU-V15 PAO1) using CLSM.
(a) PAO1, YU-V10, YU-V28 and (b) YU-V11 and YU-V15. The biofilms were treated with quercetin and antibiotics at the lowest FICi combination and stained with Acridine Orange-Propidium Iodide staining. Green color indicates the live cells and yellow to red color indicates dead cells.
Fig 7.
Cell killing effect of P. aeruginosa strains on HEK 293T cells.
The antibiotic-quercetin combinations at the lowest FICi showing attenuation of infection induced cell killing. Data are presented as mean ± SD (n = 3). Statistical differences are presented *p<0.05, **p<0.01 and ***p<0.001.