Clarithromycin Resistant Tailored Therapy

1. Back ground Antibiotics resistance of Helicobacter pylori, especially to clarithromycin is one of the main causes of failure of eradication. 23S rRNA point mutation of Helicobacter pylori is associated clarithromycin resistance 2. Hypothesis If the investigators check the 23S rRNA point mutation then choose treatment regimens containing a proton pump inhibitor and combination of two antibiotics (amoxicillin and clarithromycin or metronidazole), the investigators will eradicate Helicoabacter pylori more successfully 3. Material & methods The investigators enroll patients diagnosed with peptic ulcer, endoscopically. Helicobacter pylori is documented with Urea breath test or silver staining biopsy specimen or polymerase chain reaction of biopsy specimen. Check the 23S rRNA A2142G/A2143G point mutation by polymerase chain reaction. If there is mutation, the investigators consider as resistance to clarithromycin and choose the treatment regimen containing a proton pump inhibitor, amoxicillin, metronidazole. If there is no mutation, choose the treatment regimen containing a proton pump inhibitor, amoxicillin, clarithromycin. Verify Helicobacter pylori eradication by urea breath test. Compare eradication rate with conventional treatment,proton pump inhibitor, amoxicillin, clarithromycin.