Helicobacter pylori is a bacterial pathogen infecting the gastric antrum of half the population worldwide. H. pylori has been discovered in 1982 by J. Robin Warren and Barry J. Marshall as the major cause of gastroduodenal pathologies, including gastric and duodenal ulcer, gastric cancer and gastric B-cell lymphoma of mucosa-associated lymphoid tissue. For this great discovery Warren and Marshall deserved the Nobel Prize for Medicine and Physiology in 2005
