RELEVANCE OF ANTIBIOTIC SENSITIVITIES IN PREDICTING FAILURE OF OMEPRAZOLE, CLARITHROMYCIN, AND TINIDAZOLE TO ERADICATE HELICOBACTER-PYLORI

Omeprazole 20mg once (o.d.) or twice daily (b.d.), clarithromyrin 250m g b.d., and tinidazole 500mg b.d. for 7 days (OCT) is an elective regi men against Helicobacter pylori, bur the effect of 5-nitroimidazole re sistance is unclear, We aimed to evaluate this using the disc diffusio n technique (Mast Diagnostics, Bootle, UK) and E-test (Cambridge Diagn ostics Services, Cambridge, UK) to assess 5-nitroimidazole resistance, H. pylori was cultured from antral biopsies of infected patients, as determined by C-13-urea breath test (C-13-UBT), histology, and/or rapi d urease test, Patients were prescribed OCT and H. pylori eradication was assessed by C-13-UBT at least 4 weeks after completion of therapy, Antibiotic sensitivities to metronidazole and clarithromycin were eva luated by the disc diffusion method and by the measurement of minimum inhibitory concentration (MIG) using the E-test. One hundred and forty -one H. pylori-infected patients were enrolled in the study and the or ganism was successfully cultured from 119 patients (84%), The overall eradication rate was 125/141 (59%), 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 metronida zole: alone (P = 0.74, Fisher's exact test). MIC was assessed in 22 sa mples, Using a cut-off point of >32 mu g/ml to define metronidazole re sistance eradication rates were higher against sensitive (9/12: 75%) t han resistant (3/10; 30%) strains (P = 0.08, Fisher's exact test). 5-N itroimidazole resistance assessed by the disc diffusion technique is n ot helpful in predicting OCT failure, but the E-test may be of value.