Influence of CYP2C19 polymorphism and helicobacter pylori genotype determined from gastric tissue samples on response to triple therapy for H pylori infection

Background & Aims: The relationship between single nucleotide polymorphisms (SNPs) and clinical outcomes has been intensively studied. We intended to determine SNPs of CYP2C19 and 23S rRNA of Helicobacter pylori by using rapid urease test (RUT)-positive gastric mucosal samples. Methods: One hundred thirty-nine patients with H pylori-positive results based on RUT completed 1-week treatment with lansoprazole 30 mg twice a day, clarithromycin 200 mg 3 times daily, and amoxicillin 500 mg 3 times daily. SNPs from adenine to guanine at positions 2142 and 2143 of 23S rRNA of H pylori (A2142G and A2143G) and SNIPS from guanine to adenine at positions 681 in exon 5 (*2) and 636 in exon 4 (*3) of CYP2C19 were determined by the serial invasive signal amplification reaction assay by using DNAs extracted from gastric tissue samples already used for RUT. Minimum inhibitory concentrations of clarithromycin for H pylori were determined by culture test. CYP2C19 genotypes were classified into the rapid metabolizer (*1/*1), intermediate metabolizer (*1/*2 or *1/*3), and poor metabolizer (*2/*2, *2/*3, or *3/*3) groups. Results: H pylori strains with A2142G or A2143G mutation had higher minimum inhibitory concentrations for clarithromycin. Cure rates in rapid, intermediate, and poor metabolizer groups were 57.8% (95% confidence interval, 42.1%-72.4%), 88.2% (78.1%-94.8%), and 92.3% (74.9%-99.1%), respectively (P <.001). Cure rates in strains with and without A2142G or A2143G mutation were 48.3% (29.4%-67.5%) and 87.3% (79.5%-92.7%), respectively (P <.001). Conclusions: SNIPS of CYP2C19 and 23S rRNA of H pylori using RUT-positive gastric mucosal samples could be predictable determinants for H pylori eradication by triple therapy.