[Sensitivity of Helicobacter pylori to amoxicillin and clarythromycin with special reference to eradication therapy]

We isolated strains of Helicobacter pylori from gastric mucosa of patients with peptic ulcer before and after eradication therapy, and studied their sensitivity to amoxicillin (AMPC) and clarythromycin (CAM). Of 85 strains of H. pylori isolated before therapy, MIC90 was 0.025 microgram/ml and no strains were resistant to AMPC. On the other hand, MIC90 of CAM was 0.05 microgram/ml and seven (8.2%) were already resistant to CAM. The H. pylori strains from eight cases of failed eradication therapy with lansoprazole + AMPC remained AMPC sensitive. However H. pylori strains from nineteen cases (82.6%) out of 23 of failed eradication therapy with lansoprazole + CAM became CAM resistant. The situation was similar for the cases of failed eradication therapy with lansoprazole + AMPC + CAM. Drug sensitivity tests prior to eradication therapy are to be recommended. A disc method may be used as a simple alternative to MIC measurement.