Helicobacter pylori, a gastric pathogen associated with a broad range of
stomach diseases, has a high tendency to become resistant to
antibiotics. One of the most important factors related to therapeutic failures is its ability to change from a spiral to a coccoid form. Therefore, the main aim of our original article was to determine the influence of
myricetin, a natural compound with an antivirulence action, on the morphological transformation of H. pylori and check the potential of
myricetin to increase the activity of
antibiotics against this pathogen. We observed that sub-minimal inhibitory concentrations (sub-MICs) of this compound have the ability to slow down the process of transformation into coccoid forms and reduce biofilm formation of this bacterium. Using checkerboard assays, we noticed that the exposure of H. pylori to sub-MICs of
myricetin enabled a 4-16-fold reduction in MICs of all classically used
antibiotics (
amoxicillin,
clarithromycin,
tetracycline,
metronidazole, and
levofloxacin). Additionally, RT-qPCR studies of genes related to the H. pylori morphogenesis showed a decrease in their expression during exposure to
myricetin. This inhibitory effect was more strongly seen for genes involved in the muropeptide monomers shortening (csd3, csd6, csd4, and amiA), suggesting their significant participation in the spiral-to-coccoid transition. To our knowledge, this is the first research showing the ability of any compound to synergistically interact with all five
antibiotics against H. pylori and the first one showing the capacity of a natural substance to interfere with the morphological transition of H. pylori from spiral to coccoid forms.