Background and Aims: Despite the known risk factors, it is not clear why the same treatment protocol for Helicobacter pylori infection (H. pylori) doesnot show a similar effect in patients with common risk factors. We hypothesized that as the severity of H. pylori - induced gastric mucosa inflammation and density increase, the rate of successful treatment decreases. This study aimed to explore the existence of a possible association between gastric H. pylori colonization density and the efficacy of bismuth-containing quadruple eradication therapy.

Methods: A total of 330 patients with H. pylori positive gastritis were initially included; the diagnosis was based on the histopathological examination. H. pylori colonization density was graded according to the Sydney classification: mild (n=101), moderate (104) and severe (98). H. pylori eradication was determined via the 13C-Urea breath test performed eight weeks after therapy.

Results: There was no significant difference in terms of the distributions of age, gender, alcohol consumption, and smoking status among the groups (p>0.05). The successful eradication rates of H. pylori were 87.1%, 78.8%, and 75.5%, respectively, for the mild, moderate, and severe H. pylori colonization groups by per-protocol analysis (p=0.038). The eradication rates of H. pylori were 81.5%, 73.2%, and 67.3% respectively, for the mild, moderate, and severe H. pylori colonization groups by intention-to-treat analysis (p=0.017).

Conclusions: Helicobacter pylori colonization severity might predict the usefulness of eradication therapy in pre-treatment assessment. We recommend the use of more effective therapy regimens for H. pylori eradication in patients with severe densities.


Helicobacter pylori, H. pylori, colonization density, quadruple therapy, eradication