This preliminary study attempted to test whether pretreatment gastric histology of H. pylori infection may affect the success of dual therapy and to identify which parameter of gastric histology could be improved after dual therapy. One hundred forty-five dyspeptic patients with H. pylori infection received a two-week course of dual therapy (Amoxicillin 500 mg every 6 hr plus omeprazole 20 mg twice a day). In each patient, three pairs of gastric biopsies, sampled from the antrum, lower body, and upper body near the cardia, were collected before treatment and four weeks after completion of dual therapy. The density of H. pylori (score 1-5) and parameters of the modified Sydney system were applied to test the severity of H. pylori- related gastric histology in each specimen. The total bacterial load (score 1-15) was a sum of the density of H. pylori sampled from three biopsies. The overall rate of H. pylori eradication rate by dual therapy is 73.1% (106/145). Univariate analysis of parameters in pretreatment histology disclosed that the presence of mucosal atrophy (P < 0.01), lymphoid follicles (P < 0.005), and higher-density H. pylori (P < 0.001) predisposed to dual therapy failure. Multivariate analysis by stepwise logistic regression further confirmed that both the density of bacteria and the presence of lymphoid follicles are the two major factors related to the outcome of dual therapy (P < 0.001). Four weeks after dual therapy was completed, only patients with successful eradication significantly improved in these gastric histology parameters: acute activity, chronic inflammation, eosinophil infiltration, and mucosal atrophy. However, the lymphoid follicle and intestinal metaplasia were not significantly improved during the study period. The eradication rates among three subgroups with different total bacterial loads (group I: 1-5; II: 6-10; III: 11-15) disclosed a downward trend (I: 89.1%; II: 73%; III: 52.7%). It is concluded that dual therapy could improve gastric histology especially among patients with successful eradication of H. pylori. Evaluating pretreatment histologic parameters, including the density of H. pylori and the presence of lymphoid follicles, is valuable in predicting the success of dual therapy.
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