The fascinating bit is the original researcher proving it by ingesting the bacteria, and giving himself an ulcer, and then curing himself with antibiotics. A Nobel Prize seems reasonable.
Actually, stress does seem to be a significant cause of stomach ulcers. It seems to be a common myth that H.Pylori entirely causes ulcers, but in fact 50% of the world population are infected by H.Pylori and it generally doesn't cause ulcers. Stress seems to be a significant cause. See http://en.wikipedia.org/wiki/Peptic_ulcer#Stress
Anyway, I'm not sure what this has to do with the original post.
H pylori has fulfilled Koch's postulates as a cause of ulcer disease. I don't agree that emotional stress is a major cause of ulcer disease.
From Harrison's 17th ed. ch 287: "H. pylori and NSAID-induced injury account for the majority of DUs."
From Malfertheiner's "Peptic Ulcer Disease" (Lancet 2009): "Emotional stress and psychosocial factors are frequently identified as important contributors to ulcer pathogenesis. Although stress cannot be neglected as a contributing factor, convincing evidence for it being the sole cause of duodenal ulcer is scarce. A good example of stress as a contributory factor was the rise in bleeding gastric ulcers in elderly people after a severe earthquake in Japan."
Note that in general, when the medical establishment talks about "stress", its practitioners generally mean physiologic stress states, such as burns, trauma, sepsis, or multiorgan dysfunction. Does physiologic stress cause ulcers? Indeed. Emotional stress? It may contribute, but is not, in itself, an important cause.
