The influence of metronidazole resistance on the efficacy of ranitidine bismuth citrate triple therapy regimens for Helicobacter pylori infection.
OBJECTIVE
To assess the influence of metronidazole resistance on the efficacy of ranitidine bismuth citrate-based triple therapy regimens in two consecutive studies.


METHODS
In the first study, patients with a culture-proven Helicobacter pylori infection were treated with ranitidine bismuth citrate 400 mg, metronidazole 500 mg, and clarithromycin 500 mg, all twice daily for 1 week (RMC). In the second study, amoxycillin 1000 mg was substituted for clarithromycin (RMA). Susceptibility testing for metronidazole was performed with the E-test. Follow-up endoscopy was performed after >/= 4 weeks. Antral biopsy samples were taken for histology and urease test, and culture and corpus samples for histology and culture.


RESULTS
112 patients, 53 males, age 55 +/- 14 years (39 duodenal ulcer, 7 gastric ulcer and 66 gastritis) were treated with RMC, and 89 patients, 52 males, age 58 +/- 15 years (23 duodenal ulcer, 7 gastric ulcer and 59 gastritis) were treated with RMA. For RMC, intention-to-treat eradication results were 98% (59/60, 95% CI: 91-100%) and 95% (20/21, 95% CI: 76-100%) for metronidazole susceptible and resistant strains, respectively (P = 0.45). For RMA these figures were 87% (53/61, 95% CI: 76-94%) for metronidazole susceptible strains and 22% (2/9, 95% CI: 3-60%) for resistant strains (P = 0.0001).


CONCLUSIONS
Both regimens are effective in metronidazole susceptible strains. However, in contrast to the amoxycillin-containing regimen, that containing clarithromycin is also effective in resistant strains.
Van der Wouden
E J
EJ
Department of Internal Medicine, Bethesda Hospital, Hoogeveen, the Netherlands.
Thijs
J C
JC
Zwet
A A
AA
Kooy
A
A
Kleibeuker
J H
JH
D000328:Adult; D000658:Amoxicillin / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D001729:Bismuth / Q000627:therapeutic use*; D017291:Clarithromycin / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination; D004381:Duodenal Ulcer / Q000188:drug therapy / Q000382:microbiology; D005260:Female; D005756:Gastritis / Q000188:drug therapy / Q000382:microbiology; D005773:Gastroscopy; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000494:pharmacology*; D010406:Penicillins / Q000627:therapeutic use; D011899:Ranitidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D013276:Stomach Ulcer / Q000188:drug therapy / Q000382:microbiology
D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D010406:Penicillins; D008795:Metronidazole; C073340:ranitidine bismuth citrate; D000658:Amoxicillin; D011899:Ranitidine; D017291:Clarithromycin; D001729:Bismuth