H. pylori Testing and Histology

At each endoscopy, 10 biopsy specimens were obtained for histological analysis, Campylobacter-like organism (CLO) test, and culture to determine the presence of a current H. pylori infection. This methodology has been presented previously (Shin et al., 2013). In brief, two biopsy specimens from the greater curvature side of the antrum and two from the body were fixed in formalin to assess the presence of H. pylori by modified staining and the degree of inflammatory cell infiltration, atrophy, and intestinal metaplasia (all by hematoxylin and eosin staining). These histological features of the gastric mucosa were recorded using the updated Sydney scoring system (0, none; 1, mild; 2, moderate; and 3, marked) (Dixon et al., 1996). One specimen from each of the lesser curvature of the antrum and the body was used for rapid urease testing (CLOtest, Delta West, Bentley, Australia), and two specimens, one from the antrum and one from the body, were used for culture, and the organisms present were identified as H. pylori by Gram staining, colony morphology, and positive oxidase, catalase, and urease reactions. The remaining biopsy specimens and gastric cancer tissues were immediately frozen at -70°C until DNA extraction.