ABSTRACT
Helicobacter pylori was first discovered by Warren and Marshall as hitherto unidentified gram-negative bacillus from patients with chronic active gastritis (Figure 32.1a) and initially named Campylobacter pyloridis, since this flagellated microorganism thrives under microaerophilic condition. 1,2 Subsequent work uncovered the role of H. pylori in chronic gastritis, intestinal metaplasia, and gastric tumorigenesis, 3 and additional epidemiological, clinical, and experimental studies have confirmed the importance of H. pylori in gastric lesion processes. 3,4 The Helicobacter genus currently contains more than 50 species including gastric and enterohepatic helicobacters, 5 and differs from the genera Campylobacter and Wolinella by the presence of flagellar sheath and bulb, glycocalyx, urease and catalase, and other biochemical characteristics. 6 Since research and clinical attempts have been made mostly on H. pylori, this chapter reviews its characteristics, interaction with host environment, and pathogenesis in the gastric disease.
