Abstract
The DNA fingerprinting of Helicobacter pylori strains in two cases of acute gastritis that occurred after endoscopy was examined. H. pylori was isolated from the stomachs of two patients with acute gastritis and from the stomachs of the patients in whom the same gastrofiberscope had previously been used. The genomic DNA digested with HaeIII was subjected to pulsed-field gel electrophoresis. The corresponding paired electrophoretic patterns were completely identical. These findings provide direct evidence that postendoscopic acute gastritis can be caused by cross-infection with H. pylori via endoscopy.