[Development of resistant Helicobacter pylori in Sweden. Tendency toward increasing resistance to clarithromycin]

This study was designed to investigate the development of antibiotic resistance in Swedish H pylori isolated 1990-96. A total of 415 isolates collected from 10 clinical microbiology laboratories were examined. Three different methods of susceptibility testing were compared: agar dilution, the E-test and disc diffusion. None of the isolates was resistant to ampicillin or tetracycline, but approximately 30 per cent were resistant to metronidazole. An increase in resistance to clarithromycin was noted during 1996 (9% resistant strains), though the significance of this finding needs further investigation. The comparison of susceptibility tests suggested disc diffusion to be of doubtful value, but the E-test to be appropriate for testing H pylori. However, the number of isolates resistant to metronidazole was higher with the E-test than with agar dilution. The value of testing susceptibility to metronidazole is discussed.