This prospective, self-controlled clinical study aims to evaluate the impact of proton pump inhibitor (PPI) use on the accuracy of stool DNA testing for Helicobacter pylori (H. pylori) and to assess the applicability of this test in patients receiving PPI therapy. Patients requiring long-term PPI treatment and meeting the inclusion criteria were enrolled. After at least four weeks of PPI therapy, a stool DNA test was performed, along with collection of gastric mucosal samples via gastroscopy for tissue PCR, histology, and rapid urease testing, as well as H. pylori antibody detection. Subsequently, PPI treatment was discontinued for four weeks, after which a 13C-urea breath test and a repeat stool DNA test were conducted. By comparing the sensitivity, specificity, and consistency of stool DNA testing before and after PPI discontinuation, this study aims to characterize the interference of PPIs with the test results, thereby providing evidence to support improvements in H. pylori diagnostic methods.

Inclusion Criteria:

• Male or female patients aged 18-80 years;
• No prior H. pylori eradication therapy;
• Patients requiring proton pump inhibitor (PPI) therapy in the near future due to gastritis, peptic ulcer disease, or other indicated conditions;
• Patients with at least two positive results among H. pylori antibody test, histology, and rapid urease test (RUT);
• Provision of signed informed consent and being informed of the specific study protocol.

Exclusion Criteria:

• Prior H. pylori eradication therapy;
• Pregnant or lactating women;
• Acute gastrointestinal bleeding;
• History of subtotal gastrectomy;
• Severe dysfunction of vital organs (heart, liver, kidney, lungs, etc.) or congenital diseases, such as class IV cardiac insufficiency, liver failure, uremia, respiratory failure, hemophilia, Wilson's disease, etc.;
• Refusal of enrollment by the guardian or the patient;
• Alcohol and/or drug abuse (addiction or dependence), or poor compliance as judged by the investigator;
• Individuals without legal capacity or with impaired insight;
• Abnormal neurological signs on physical examination;
• Use of oral antibiotics with bactericidal activity against H. pylori within 4 weeks.

Patients aged 18-80 years requiring PPI therapy for gastritis or peptic ulcer disease, with no prior H. pylori eradication therapy, and confirmed H. pylori infection (≥2 positive among antibody, histology, and RUT). Exclusion criteria include pregnancy, lactation, acute gastrointestinal bleeding, subtotal gastrectomy, severe organ dysfunction, recent antibiotic use (within 4 weeks), substance abuse, and conditions affecting compliance or safety. All participants provide written informed consent.