Robin Warren (born 1937), a pathologist from Perth, Australia, observed small curved bacteria colonizing the lower part of the stomach (antrum) in about 50% of patients from which biopsies had been taken. He made the crucial observation that signs of inflammation were always present in the gastric mucosa close to where the bacteria were seen.
Barry Marshall (born 1951), a young clinical fellow, became interested in Warren’s findings and together they initiated a study of biopsies from 100 patients. After several attempts, Marshall succeeded in cultivating a hitherto unknown bacterial species (later denoted Helicobacter pylori) from several of these biopsies. Together they found that the organism was present in almost all patients with gastric inflammation, duodenal ulcer or gastric ulcer. Based on these results, they proposed that Helicobacter pylori is involved in the aetiology of these diseases.
Even though peptic ulcers could be healed by inhibiting gastric acid production, they frequently relapsed, since bacteria and chronic inflammation of the stomach remained. In treatment studies, Marshall and Warren as well as others showed that patients could be cured from their peptic ulcer disease only when the bacteria were eradicated from the stomach. Thanks to the pioneering discovery by Marshall and Warren, peptic ulcer disease is no longer a chronic, frequently disabling condition, but a disease that can be cured by a short regimen of antibiotics and acid secretion inhibitors.
SOURCE: Nobel
There is another chapter to this story other than just the discovery. At the time they were publicly ridiculed by the scientific community for their theory, and they basically had to prove it beyond any doubt in order to get it accepted. Marshall went to the extreme length of infecting himself and then healing the resulting ulcer with antibiotics.
Another problem was the drug industry—anti-ulcer medications (that relieved the symptoms not the ulcer itself) were very lucrative, and the pharmaceutical companies did not want to lose that income. It would be similar to the oil industry’s reaction to the invention of a cheap, plentiful energy source that could power cars.
More details at the New Scientist.
…I mentioned this earlier in a comment to apsmith…
Basically, big pharma was pump-priming its ulcer drugs anticipating profits of a billion a year (per drug) for years on end. Last thing they needed was some upstart turning up and saying he could cure ulcers in a couple of weeks with a handful of cheap (generic) antibiotics. Where was the profit in that!