Prevalence of metronidazole-resistant Helicobacter pylori in dyspeptic patients

Susceptibility to metronidazole of 213 clinical strains of H. pylori from dyspeptic patients was determined by a plate dilution method. Seventy two (33.8%) of the strains were resistant to metronidazole (MIC > 8 mg/L), 20 of these were from 24 patients who had received previously metronidazole (83.3%), giving a primary (pretreatment) resistance rate of 27.5% (52/189). The resistance rate was higher in women than in men, especially aged 50 to 59 years old (43.6% vs 23.3%, p < 0.001). The resistance rate was lower in patients at 60 or over (9.8%), but similar between the younger patients groups (38.8% - 49.0%). There was no difference in the resistance rate between peptic ulcer disease (32.6%) and nonulcer dyspepsia (34.7%). These data indicated that metronidazole resistance in H. pylori is absolutely associated with previous use of the drug, and the higher resistance rate in women may be due to the more frequent prescription of the drug for their gynaecological infection or operation. Therefore, testing of susceptibility of H. pylori to metronidazole is important. A new susceptibility testing technique, the E-test was evaluated in this study and found to give comparable results to the plate dilution method and also had the advantage of being simple to perform.