Chemotaxis and motility of Helicobacter pylori in a viscous environment

The chemotactic activity of Helicobacter pylori is important for its colonization. H. pylori exhibited chemotactic responses to urea and potassium bicarbonate, which can be supplied from human gastric epithelium. The chemotactic activities of H. pylori in a fluid environment were higher on the urease-positive strain than on the isogenic urease-negative strain. In a viscous solution containing 3% polyvinylpyrrolidone, the urease-positive strain showed stimulated chemotactic activity, whereas the urease-negative mutant did not show such stimulation. These results were in accordance with the fact that the mutant strain did not show swarming, which is a form of bacterial active motility in the viscous environment in soft agar regardless of having flagella. Incubation of the wild-type strain with urease inhibitors partially inhibited the chemotactic activities in the viscous solution. Inhibition of the chemotactic activity by urease inhibitors paralleled the inhibition of urease activity. The chemotactic activity of H. pylori has been shown to utilize proton motive force for motility. These results highlighted the importance of cytoplasmic urease for chemotactic motility of H. pylori possibly by an increase in the proton motive force under a condition that mimics the gastric mucus layer, in which the bacteria reside. These results indicated a possible application of drugs having urease-inhibiting potential for eradicating H. pylori. The significance of swarming in the expression of bacterial virulence was also discussed.