http://en.wikipedia.org/wiki/Helicobacter_pylori
"Helicobacter pylori is a gram-negative, microaerophilic bacterium that infects various areas of the stomach and duodenum. Many cases of peptic ulcers, gastritis, duodenitis, and cancers are caused by H. pylori infections...
The bacterium was rediscovered in 1979 by Australian pathologist Robin Warren, who did further research on it with Barry Marshall beginning in 1981; they isolated the organisms from mucosal specimens from human stomachs and were the first to successfully culture them.[5] In their original paper,[6] Warren and Marshall contended that most stomach ulcers and gastritis were caused by infection by this bacterium and not by stress or spicy food as had been assumed before."