CYP2C19 Genotype, CagA Genotype and Antibiotic Resistant Strain of Helicobacter pylori Infection

Document Type : Research Articles


1 Gastroenterology Unit, Department of Medicine, Faculty of Medicine, Thammasat University Hospital, Pathumthani, Thailand.

2 National Gastric Cancer and Gastrointestinal Diseases Research Center (NGGC), Department of Medicine,Pathumthani, Thailand.

3 Chulabhorn International College of Medicine (CICM) at Thammasat University, Pathumthani, Thailand.

4 Department of Environmental and Preventive Medicine, Faculty of Medicine, Oita University, Oita, Japan.


Background: H. pylori is a class I carcinogen and major cause of gastric cancer. Few previous studies reported
relationship between H. pylori infection, CYP2C19 genotype and functional dyspepsia (FD) subtype. The aim of this
study was to determine relationship between CYP2C19 genotype and FD subtype patients(host factor) with antibiotic
resistant strains of H. pylori infection and CagA genotype(bacterial factor). Methods: FD patients who were investigated
with gastroscopy at Thammasat University Hospital, Thailand during March 2017-November 2017 were enrolled. Two
antral gastric biopsies were obtained for rapid urease test, E-test and cultures. CagA genotypes (CagA1a and CagA2a)
were determined by PCR and CYP2C19 genotype was determined by PCR-RFLP. FD patients were categorized as
epigastric pain syndrome(EPS) and postprandial distress syndrome (PDS). Results: 93 FD patients with H. pylori
infection were enrolled (37 male, 56 female, mean age 54.5 years). There were 33 patients with EPS and 60 patients
with PDS. CYP2C19 genotype revealed 55.9% rapid metabolizer (RM), 40.9% intermediate metabolizer (IM) and
3.2% poor metabolizer (PM) genotypes. Antibiotics susceptibility tests demonstrated 62.8% resistant to metronidazole,
12.9% resistant to clarithromycin and 27.1% resistant to fluoroquinolone. CagA 1a and CagA 2a were demonstrated
in 6 patients(11.5%) and 46 patients(88.5%). CagA2a genotype was more prevalent in PDS than EPS patients
(94.3%vs.76.5%; P =0.08) without significance. In intermediate metabolizer (IM), CagA2a genotype was significant
higher in PDS than EPS(100% vs.25%; P=0.004). Conclusions: PDS, CYP2C19 RM genotype and CagA 2a gene of
H. pylori infection were the predominant type of FD in Thailand. Metronidazole remain the most common antibiotic
resistant strain of H. pylori infection in FD patients. PDS (host factor) was significantly related to CagA2a genotype
(bacterial factors) only in patients with intermediate metabolizer. Appropriate dose of proton pump inhibitor (PPI) and
correct regimens for H. pylori eradication in FD patients should be consider to improve clinical outcomes.


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