Study on Second-line Helicobacter pylori Infection Eradication Therapy Based on CYP2C19 Genetic Polymorphism

Proton pump inhibitor(PPI)-based triple therapy with 2 antibiotics is a routine treatment for the eradication of Helicobacter pylori(H.pylori)infection in patients with gastric and duodenal ulcers.While this regimen achieves a high eradication rate for H.pylori infection,approximately 20% of patients fail to respond to it and several recent studies have shown that clarithromycin(CAM)resistance,PPI metabolic enzyme genetic polymorphism,smoking habit,and non-adherence to medication are associated with unsuccessful eradication of H.pylori infection.In view of this,we introduced a second-line H.pylori infection eradication therapy based on testing for CYP2C19 genetic polymorphism as a routine hospital procedure.A total of 51 patients in whom the initial PPI-based regimen failed underwent the second-line therapy based on their genotypes with respect to CYP2C19.Of the 48 patients evaluated,44 were extensive CYP2C19 metabolizers(EM : homoEM,23 ;heteroEM,21)and 4 were poor metabolizers(PM).The results of an antibiotic sensitivity test revealed CAM-resistant strains in 22 patients but AMPC-resistant strains were not evident.The EM group was retreated with 30 mg lansoprazole(LPZ)and 500 mg amoxicillin(AMPC)4 times a day for 2 weeks and the PM group was re-treated with 30 mg LPZ twice a day and 500 mg AMPC 4 times a day for 2 weeks.The second-line therapy succeeded in 94% of the patients(45 of 48 patients).We established CYP2C19 genetic polymorphism testing as a routine hospital procedure in H.pylori infection eradication therapy using PPI+AMPC.The second-line therapy based on this regimen was sufficiently effective despite the absence of CAM sensitivity.