The Fine Form of Helicobacter pylori on the Metaplastic Duodenal Mucosa Is Associated with Recurrent Duodenal Ulcers

Background/Aim: It is well known that Helicobacter pylori changes its shapes according to various environmental conditions. The aim of this study was to examine the morphological differences between H. pylori in the duodenum and that in the stomach. Methods: Duodenal biopsy specimens were obtained from patients with duodenal mucosal lesions, and these specimens were then histopathologically examined. Morphological and genetic properties of cultured H. pylori isolates were analyzed. Results:H. pylori was identified in 16 out of 50 duodenal biopsy specimens. Along with the regular form, we found a fine form of H. pylori in the gastric metaplastic mucosa of ten duodenal specimens that was shorter in length and thinner in diameter than the regular helical form. There were no detectable differences between the ureA-ureB polymorphism of the duodenal fine form and that of gastric regular form in a single patient. As compared with patients without H. pylori in the duodenum, the prevalence of recurrent duodenal ulcers significantly increased in patients with the fine form (p < 0.05), but not in patients with the regular form. Conclusion: The fine form of H. pylori in the metaplastic duodenal mucosa could result from its adaptation to the duodenal environment and may be associated with the recurrence of a duodenal ulcer.