Final answer:
H. pylori creates a neutral pH microenvironment in the acidic stomach by producing urease, which generates ammonia to neutralize the acidity, enabling its survival and persistence.
Step-by-step explanation:
Helicobacter pylori (H. pylori) is a gram-negative bacterium known for its ability to persist in the highly acidic environment of the human stomach. Despite being a neutrophile, H. pylori survives by creating a microenvironment where the pH is nearly neutral. It does this by producing large amounts of the enzyme urease, which breaks down urea into ammonium ions (NH4+) and carbon dioxide (CO₂). The ammonium ions raise the local pH, thus helping the bacterium to survive.
H. pylori also adheres to gastric epithelial cells using pili, modifies the mucin layer with its virulence factors, and induces an immune response leading to inflammation and potential ulcer formation. The bacterium's presence is closely associated with peptic ulcers and an increased risk of stomach cancer.