Defining Helicobacter pylori as a Pathogen: Strain Heterogeneity and Virulence

Helicobacter pylori, the etiologic agent of gastritis and peptic ulceration, may infect the gastric mucosa of over half of the world's population. Despite the high infection rate, symptomatic disease beyond gastritis (characterized by gastric or duodenal ulcer) is noted in a small, but nevertheless significant, fraction of this population. What defines an H. pylori strain as a pathogen that can cause the more serious clinical manifestations? In …