Helicobacter pylori is a bacterium that inflicts many gastric infections; it lives in the stomach lining and duodenum . It is the most common cause of gastritis and peptic ulcers . The bacteria multiply in the mucosal layer of the stomach lining and duodenum. H. pylori (Helicobacter pylori) is one of the most common gastric bacteria due to its secretion of urease . The enzyme urease breaks down urea into ammonia (NH₃) and carbon dioxide . The pH around the bacterium is then raised significantly by the reaction between the stomach's hydrochloric acid and the ammonia . Being one of the most prevalent bacteria, H. pylori can flourish and thrive against stomach acids because of this essential neutralizing reaction .