BACKGROUND AND AIM: Helicobacter pylori (H. pylori) infection induces inflammation of the gastric mucosa and leads to erosions, gastro-duodenal mucosa atrophy, and intestinal metaplasia. The Kyoto classification diagnoses H. pylori infection via endoscopic findings. We aimed to clarify the role of the Kyoto classification in diagnosing H. pylori infection and histologic gastritis in young Japanese individuals. METHODS: From1031 consecutive subjects aged ≤29 years who underwent esophagogastroduodenal endoscopy at our two hospitals from 2010 to 2017, 220 were selected for participation in the present study. Endoscopic biopsy specimens from the antrum and corpus were used to investigate H. pylori infection and histology. Endoscopic and histological interpretations were based on the Kyoto classification and updated Sydney System. H. pylori infection was confirmed by histology and Giemsa or Gimenez staining. RESULTS: Endoscopic findings were normal in 103 cases. Atrophy was found in 56 cases; diffuse redness, in 45 cases; nodularity, in 38 cases; and mucosal swelling, in 34 cases. The infection rate was 30.9% (68/220). In total, 67 subjects with H. pylori -positive endoscopic findings and confirmed as H. pylori -positive had histologic gastritis of the antrum and corpus. In contrast, of 153 subjects with H. pylori -negative endoscopic findings only 1 was subsequently confirmed to be H. pylori positive. Among the 67 subjects with H. pylori -positive endoscopic findings, 23 (34.3%) presented with histological atrophic gastritis of the corpus and 6 (9.0%) with intestinal metaplasia. CONCLUSIONS: Our findings show that H. pylori infection is strongly associated with endoscopic and histologic gastritis in young subjects and both H. pylori infection and histologic gastritis can be evaluated endoscopically based on the Kyoto classification. Furthermore, prompt H. pylori eradication may prevent gastric cancer development given the high prevalence of atrophic gastritis and intestinal metaplasia in young Japanese individuals
