- There have been many reports of the development of achlorhydria in individuals and in groups of subjects with previously normal levels of gastric acid secretion. The evidence that this phenomenon is due to an infective agent has been considered. Retrospective identification of CLO in gastric mucosal biopsies from some of these patients is an interesting observation, but does not conclusively prove a causal relationship. The exact significance of CLO remains speculative at present; there is more evidence to suggest that it plays a role in gastritis than in peptic ulceration. Ongoing research in this area may have major consequences for the medical treatment of gastritis, 'non-ulcer dyspepsia' and perhaps also for peptic ulcer disease.