Helicobacter pylori

Helicobacter pylori (HP) is a spiral-shaped Gram-negative bacterium in the human gastric mucosa. The HP organism is smooth, S-shaped, with 4-6 flagella. It easily adheres to the mucosa of the gastric antrum near the pylorus and the gastric body, located in the deep layer of gastric mucus, not in direct contact with gastric acid. HP is transmitted between people through the oral route. Viable HP can survive for 1 week in river water. HP can produce various enzymes such as urease, catalase, protease, and phospholipase. Among them, urease can decompose urea to produce ammonia, which both protects the bacteria from gastric enzyme attack and has a direct toxic effect on gastric mucosal cells. Catalase can inhibit the formation of some bactericidal substances. Protease and lipase can destroy the integrity of the gastric mucosa. The vacuolating toxin produced by HP can cause vacuolar degeneration of the gastric mucosa. HP is one of the important causes of chronic gastritis and peptic ulcers, and is also closely related to the pathogenesis of gastric cancer.