Helicobacter pylori Infection: Options for Testing and Treatment.

H elicobacter pylori are helical, rod-shaped, Gramnegative bacteria that penetrate the mucous layer of the stomach to colonize the luminal surface of the gastric epithelium. Several features make these bacteria particularly suited to the harsh environment of the stomach. For example, their elevated urease activity allows them to efficiently convert urea (present in the gastric juice) to alkaline ammonia and carbon dioxide. Additionally, these bacteria have prominent flagella that help them to penetrate the thick mucosa of the stomach. Chronic infection with H. pylori is widespread, occurring in approximately half of the world’s population, and infection is typically acquired early in life, especially among those in lower socioeconomic groups.1 While H. pylori infection results in chronic inflammation of the underlying gastric mucosa, the vast majority of infected patients do not experience any clinically significant symptoms. However, H. pylori infection is linked with the development of certain upper gastrointestinal diseases. For example, 1–10% of duodenal and gastric ulcers are thought to be related to H. pylori infection. The inflammation associated with chronic H. pylori infection, which is largely located within the non–acidsecreting antral region of the stomach, causes increased gastrin release, which in turn induces excess acid secretion from the fundic mucosa and damage and ulceration of the duodenal mucosa.2,3 Treatment and eradication of H. pylori infection cure duodenal or gastric ulcers in over 80% of patients. Chronic H. pylori infection is also strongly associated with the development of gastric cancers, especially those distal to the gastroesophageal junction.4 This risk is highest among patients who experience H. pylori– related inflammation in both the antral and fundic mucosa; this inflammation can lead to mucosal atrophy and intestinal metaplasia.5 Whether eradication of the infection reduces the risk of gastric cancer remains unclear. Additionally, several studies have demonstrated a link between H. pylori infection and gastric mucosa– associated lymphoid-tissue (MALT) lymphoma.6 Localized regression of most MALT lymphomas is typically observed with eradication of the infection.7 Many patients diagnosed with functional dyspepsia are found on biopsy to have H. pylori infection and associated inflammation. However, there is little evidence that the infection itself results in upper gastrointestinal symptoms, as H. pylori infection and inflammation are also common among individuals with no upper gastrointestinal symptoms. Additionally, H. pylori eradication therapy has minimal to no effect on symptoms in these cases.