Antibiotic resistance problems with Helicobacter pylori

Helicobacter pylori is very susceptible in vitro to most antibiotics, but w hen they are used in the clinical setting, eradication of the bacteria from the gastric mucosa is not obtained. Dual or triple therapy including two o f the following antibiotics: amoxicillin, tetracycline, metronidazole or cl arithromycin, plus a proton pump inhibitor, bismuth salt or ranitidine bism uth citrate is the most frequently used. Various in vitro susceptibility me thods have been used: disk diffusion, agar dilution and Epsilometer test (E -test). Metronidazole resistance among H. pylori strains is now found world wide, and resistance rates vary according to the population studied. It is higher in developing than in developed countries and it could reach 80-90% in Africa. The prevalence on clarithromycin resistance is much lower, usual ly below 10%, although very high values are reported in Peru. Infection wit h metronidazole- or clarithromycin-resistant H. pylori strains is correlate d with treatment failure when using regimens including these antibiotics. ( C) 1999 Elsevier Science B.V. and International Society of Chemotherapy. Al l rights reserved.