Figure 5.

Graphical representation of the results of checkerboard assays testing synergistic interactions between myricetin and antibiotics against reference H. pylori J99 and Tx30a strains. The MIC of myricetin for both strains is equal to 160 µg/mL. The MICs for amoxicillin, tetracycline, and metronidazole for both strains count for 0.12, 0.1, and 1 µg/mL, respectively. The MICs for clarithromycin and levofloxacin are equal to 0.025 and 1 µg/mL for H. pylori J99, and 0.05 and 0.25 µg/mL for H. pylori Tx30a. The blue field marks the wells of the titration plates, in which no bacterial growth and a positive interaction between the tested compounds was observed. The interactions were interpreted based on the calculation of the fractional inhibitory concentration index (FICI), in which ≤0.5 and >0.5 but ≤1 was considered as synergism and additivity, respectively.