The rapid urease test (RUT) is frequently performed for diagnosis of Helicobacter pylori infection in clinical practice. The RUT is a simple and inexpensive method that utilizes a commercial kit containing urea and a pH indicator such as phenol red. In the presence of H. pylori urease, urea is hydrolyzed to ammonia, which raises the pH of the medium, and changes the color of the kit from yellow to magenta or pink. The sensitivity and specificity of RUT were reported to range between 80-100% and 97-99%, respectively. When endoscopy is performed, RUT is known as the first-line method used for H. pylori diagnosis. However, RUT is an indirect test method, and has the disadvantage of causing false positivity due to other urease-producing bacteria.

To date, gold standards for H. pylori diagnosis are culture and histological examination Because H. pylori is a rather fastidious and slow-growing bacterium, antimicrobial susceptibility testing using culture methods is time-consuming (10-14 days) and requires specific expertise. Recently, dual priming oligonucleotide (DPO)-based multiplex polymerase chain reaction (PCR) was developed to diagnose H. pylori infection. Moreover, molecular testing can identify point mutations related to clarithromycin resistance. It can be performed in a standard thermocycler and takes only 4 h to complete. The concordance rate between conventional clarithromycin susceptibility testing and DPO-PCR was excellent up to 95%. However, there was no comparison study between RUT and molecular testing for H. pylori diagnosis.

The investigators aim to compare the diagnostic accuracy of the RUT and molecular testing, and identify clinical factors associated with the discordant results between the two methods.

Inclusion Criteria:

• Gastroscopy can be performed
• H. pylori test and pathological analysis can be performed

Exclusion Criteria:

• Age < 20 or > 80 years
• Anemia (serum hemoglobin level < 10 g/dL)
• Severe systemic disease
• Advanced chronic liver disease
• Use of certain medications, including proton pump inhibitors, H2- receptor antagonists, or antibiotics
• History of H. pylori eradication
• Drug allergy to antibiotics
• History of gastric surgery
• Recent history of upper gastrointestinal bleeding

H. pylori-infected patients