The goal of this clinical trial is to study the differences in gastric microbiota (Diversity index) between patients who were infected with CagA-positive Helicobacter pylori and CagA-negative Helicobacter pylori. The main question it aims to answer are:

The effect of Helicobacter pylori typing (CagA status) on gastric microbiota, what is the different?

Patients indicated for EGD at Siriraj Endoscopic Center will undergo a Helicobacter pylori test (Rapid urease test) If the result is positive, a stomach biopsy for gastric microbiota testing and CagA antibody testing will be conducted. Then, the patients will be divided into two groups: CagA-positive Helicobacter pylori and CagA-negative Helicobacter pylori.

To compare the differences in gastric microbiota in terms of species and biodiversity, as well as endoscopic results, etc.

Inclusion Criteria:

• Patients aged over 18 with an indication for EGD
• Helicobacter pylori infection (Rapid urease test positive)

Exclusion Criteria:

• Severe comorbidities: poorly controlled DM, ESRD, decompensated cirrhosis, Malignancy
• BMI ≤ 23 kg/m2
• Receiving medications that affect the gastric microbiota include Antibiotics, probiotics, or bismuth within 4 weeks, PPI within 2 weeks, NSAIDs or Metformin within 2 weeks
• History of cholecystectomy or proximal small bowel surgery