Helicobacter pylori is a spiral-shaped Gram-negative bacillus that colonises the surface epithelium of the human stomach. Its existence was first confirmed in 1983.¹ Prior to this, controversy had surrounded reported observations of bacteria in the stomach. Its discoverers observed that the bacterium was almost always associated with an active chronic gastritis, histologically occurring predominantly in the gastric antrum, and this led them to propose that it might be causally related to peptic ulcer disease and gastric cancer. Since this prescient claim, the aetiological role of H. pylori in both of these diseases has been confirmed by epidemiological studies^2–6 and, as a result, in 1994 the bacterium was classified as carcinogenic to humans by the World Health Organization (WHO).⁷ Between 15 and 30% of individuals in the Western world are infected by the organism,^8–10 compared with 80% or more in the Far East.¹¹