Relevance of antibiotic sensitivities in predicting failure of omeprazole, clarithromycin, and tinidazole to eradicate Helicobacter pylori.
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Omeprazole 20mg once (od) or twice daily (bd), clarithromycin 250mg bd, and tinidazole 500 mg bd for 7 days (OCT) is an effective regimen against Helicobacter pylori, but the effect of 5-nitroimidazole resistance is unclear. We aimed to evaluate this using the disc diffusion technique and E-test to assess 5-nitroimidazole resistance. H. pylori was cultured from antral biopsies of infected patients as determined by 13C-urea breath test (13C-UBT), histology, and/or rapid urease test. Patients were prescribed OCT, and H. pylori eradication was assessed by 13C-UBT at least 4 weeks after completion of therapy. Antibiotic sensitivities to metronidazole and clarithromycin were evaluated by the disc diffusion method and by minimum inhibitory concentration (MIC) using the E-test. One hundred and forty-one H. pylori-infected patients were enrolled into the study and the organism was successfully cultured in 119 patients (84%). The overall eradication rate was 125/141 (89%). OCT was successful in 62/69 (90%) patients harboring fully sensitive strains of H. pylori compared with 42/45 (93%) of patients with strains that were resistant to metronidazole alone (P = 0.74, Fisher's exact test). MIC was assessed in 22 samples. Using a cut-off point of > 32 microg/ml to define metronidazole resistance, eradication rates were higher against sensitive (9/12; 75%) compared with resistant (3/10; 30%) strains (P = 0.08, Fisher's exact test). 5-Nitroimidazole resistance assessed by the disc diffusion technique is not helpful in predicting OCT failure, but the E-test may be of value.
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