This randomized, open-label clinical trial will compare two bismuth-containing quadruple therapies for the first-line treatment of Helicobacter pylori infection. Adults aged 18 years or older with confirmed H. pylori infection who have not previously received eradication treatment will be randomly assigned in a 1:1 ratio to receive either a metronidazole-based regimen or a tinidazole-based regimen for 14 days. Both regimens will also include esomeprazole, tetracycline, and bismuth subcitrate.

The main purpose of the study is to determine whether the tinidazole-based regimen is not inferior to the metronidazole-based regimen in achieving successful H. pylori eradication. Eradication will be assessed after treatment using a carbon-13 urea breath test or an endoscopic urease test. The study will also compare adverse effects and treatment tolerability between the two groups. The results may help clinicians select the more appropriate nitroimidazole for bismuth quadruple therapy in routine clinical practice.