title: Relevance of antibiotic sensitivities in predicting failure of omeprazole, clarithromycin, and tinidazole to eradicate Helicobacter pylori.
abstract: Omeprazole 20 mg once (o.d.) or twice daily (b.d.), clarithromycin 250 mg b.d., and tinidazole 500 mg b.d. 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 (Mast Diagnostics, Bootle, UK) and E-test (Cambridge Diagnostics Services, Cambridge, UK) 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 the measurement of minimum inhibitory concentration (MIC) using the E-test. One hundred and forty-one H. pylori-infected patients were enrolled in the study and the organism was successfully cultured from 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%) than 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.
authors.affiliation: Gastroenterology Department, Centre for Digestive Diseases, General Infirmary at Leeds, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Moayyedi
authors.forename: P L
authors.initials: PL
authors.lastname: Ragunathan
authors.forename: N
authors.initials: N
authors.lastname: Mapstone
authors.forename: A T
authors.initials: AT
authors.lastname: Axon
authors.forename: D S
authors.initials: DS
authors.lastname: Tompkins
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D000897:Anti-Ulcer Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D017291:Clarithromycin / Q000008:administration & dosage / Q000627:therapeutic use*; D004352:Drug Resistance, Microbial; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009593:Nitroimidazoles / Q000494:pharmacology*; D009853:Omeprazole / Q000008:administration & dosage / Q000627:therapeutic use*; D014011:Tinidazole / Q000008:administration & dosage / Q000627:therapeutic use*; D017211:Treatment Failure
chemical_list: D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D009593:Nitroimidazoles; D014011:Tinidazole; D017291:Clarithromycin; D009853:Omeprazole; C052587:4-nitroimidazole