The new main contributions of the thesis The recurence of H pylori after eradication is quite common in many countries at different rates. The study identified recrudescence or reinfection in patients with H pylori re-positive after successful eradication has important implications for the treatment strategy. This is the first study using PCR-RFLP technique and genetic sequencing to determine UreC genotype of H pylori strains taken directly from stomach biopsy.