Bacteria in ulcer pathogenesis

A great deal of information about the spiral bacteria of the stomach has accumulated in the past 5 years. These bacteria, currently named Campylobacter pylori but likely to be renamed as a new genus, have adapted to living beneath the mucus layer and above the gastric surface mucous cells. When metaplastic gastric mucous cells are also present in the duodenal bulb, C. pylori may also get a foothold in this latter location. Observations of the high prevalence of C. pylori in patients with gastritis and with duodenal ulcers, and the slightly lower prevalence in patients with gastric ulcer, have led to the hypothesis that the bacteria play an aetiological role in these three conditions. There is now fairly convincing evidence that the organisms can cause active chronic gastritis. The most persuasive of this comes from reports of the rapid development of gastritis and symptoms in two volunteers who swallowed the organism, plus two other series of accidental challenges. Other evidence is provided by the waning and waxing of gastritis, which has been correlated in several studies with clearance followed by recrudescence of the organisms. The role of the bacterium in peptic ulcer is less certain. The present data do not provide strong evidence for a causal role in gastric ulcer, although we cannot rule out that it may be important in some. The very high prevalence in patients with duodenal ulcer, including one series in children (who rarely harbour the organism), raises the distinct possibility that the bacteria play an aetiological role in this form of ulcer. Reports of ulcer healing with antibiotics and of lower recurrence rates in those cleared of the organism, increase the possibility, However, methodological flaws in some studies, plus the usual need for confirmation of key studies, indicate that we should await more definitive evidence before accepting that duodenal ulcer can be an infectious disease.