[Evaluation of CO2 condition for antibiotic susceptibility test of Helicobacter pylori on microdilution broth]

We determined the MICs of clarithromycin for 32 Helicobacter pylori strains isolated from gastric mucosa of patients, by using microdilution broth method under different microaerobic conditions (CO2: 5% and 15%). The pH of broth was more acidic at 15% CO2 than that of at 5% CO2. The MICs of clarithromycin for all H. pylori strains at 15% CO2 condition were higher than that of clarithromycin at 5% CO2 condition. Comparing the MICs with the results of eradication therapy, we concluded that the measurement of MIC under 5%CO2 condition is more useful for expecting the clinical outcome.