Which bacterium is commonly associated with acute and chronic gastritis?

Helicobacter pylori is the bacterium most commonly associated with both acute and chronic gastritis. This gram-negative bacterium is notably adept at surviving in the acidic environment of the stomach, where it can colonize and cause inflammation of the gastric mucosa. The presence of H. pylori can lead to chronic gastritis and is also a significant risk factor for the development of peptic ulcers and gastric cancer.

The pathogenicity of H. pylori is attributed to several factors, including its ability to produce urease, which helps neutralize stomach acid, allowing the bacteria to thrive. Additionally, H. pylori's flagella enable it to move through the stomach lining, and its virulence factors can disrupt the normal protective mucus layer, leading to inflammation and other gastrointestinal issues.

Other bacteria listed, such as Escherichia coli, Staphylococcus aureus, and Salmonella enterica, are associated with different types of infections, primarily outside the stomach's chronic inflammatory processes. While they're linked to gastrointestinal maladies, they do not have the same established correlation with gastritis as Helicobacter pylori does.