Comparison of activity of 10 antibiotics against clinical strains of Helicobacter pylori by three different techniques.

The authors determined the susceptibility of 55 single clinical strains of Helicobacter pylori isolated in the Montreal area to 10 antibiotics by three different methods--an agar dilution technique considered to be the gold standard, a disk diffusion method and the E-test. Testing was performed on Mueller-Hinton agar supplemented with 10% sheep blood; plates were incubated at 37 degrees C for 72 h in a microaerophilic atmosphere. The metronidazole resistance rate is about 11% in the Montreal area. Macrolides are very active against H pylori isolates, with few variations in activity between older and newer molecules. Correlation among different methods was not as good as reported in the literature for metronidazole.