A method for assessment of Helicobacter pylori genotype using stool specimens

Helicobacter pylori infection has been regarded as a major factor associated with the development of gastric diseases. The characterization of infected H. pylori in asymptomatic individuals is important for the prediction of the onset of such diseases. However, because of the difficulty in obtaining gastric biopsy samples, H. pylori in healthy subjects have not been studied sufficiently. Therefore, we tested a noninvasive method for the characterization of H. pylori using stool specimens. This method involved H. pylori antigen detection in stool specimens by immuno-chromatography; confirmation of H. pylori DNA by real-time PCR that involved the detection of its 16S rRNA gene in the DNA extracted from stool specimens; and nested PCR with genotype-specific primer pairs. A total of 80 samples obtained from asymptomatic subjects were assessed using this method. The results showed that the prevalence of H. pylori in asymptomatic Japanese individuals was 37.5%. The detection rate of the virulence factor gene cagA was 18.8%. Furthermore, all the detected cagA belonged to the highly virulent East-Asian type. These data suggest that the method used in this study is valuable for studying the molecular epidemiology of H. pylori infection in asymptomatic people.