The aim of this study is to Identify antibiotic resistance gene mutations in Helicobacter pylori (HP) and genetic diversity of drug metabolism for antibiotics and proton pump inhibitors (PPIs) in patients with HP infection using next-generation sequencing (NGS). The mutation of host/HP strain will be investigated by single NGS, and the eradication results according to genetic polymorphism of host/HP strain will be analyzed.

This study is a prospective observational study for the Helicobacter pylori (HP) infected patients on typical gastroduodenoscopy (EGD) at Boramae Hospital, Seoul, Korea.

The presence of antibiotic resistance genes of HP and the diversity of the pharmacokinetic genotypes of the subjects will be investigated by performing single next-generation sequencing (NGS) analysis using gastric mucosal tissue samples of the HP infected subjects.

The purpose of this study is to collect data on the antimicrobial resistance mutation of HP (23S rRNA gene, pbp1 gene, rdxA, frxA, frxB gene, 16S rRNA, gyrA, gyrB gene, and Cag A gene) and to investigate the genetic diversity on the metabolism of antibiotics and proton pump inhibitors (CYP enzyme) in a Korean population.

The investigators are going to compare the results of standard eradication therapy according to the resistance mutation of HP and drug genetic diversity of subjects.

Inclusion Criteria:

• Age over 18 years old
• CLO test positive
• Findings of gastric ulcer, atrophic gastritis on gastroduodenoscopy
• Agreed to HP eradication therapy and accept to follow-up
• Agreed to participating in the study

Exclusion Criteria:

• History of previous HP eradication treatment
• History of partial gastrectomy

H. pylori-positive healthy patients