The impact of antibiotic resistance on the efficacy of three 7-day regimens against Helicobacter pylori

Background: Antibiotic resistance affects the success of anti-Helicobacter pylori therapies and varies greatly from country to country. Aim: To compare the efficacy of three short-term triple regimens in relatio n to H. pylori primary resistance in our region. Methods: We enrolled 210 H. pylori-positive dyspeptic patients for this ran domized, open, parallel-group study. Three arms of 70 patients each receive d the following 1-week regimens: (1) ranitidine bismuth citrate 400 mg b.d. + clarithromycin 250 mg b.d. + metronidazole 500 mg b.d. (RCM); (2) bismut h subcitrate 240 mg b.d. + amoxycillin 1000 mg b.d. + metronidazole 500 mg b.d. (BAM); (3) omeprazole 20 mg o.d. + clarithromycin 250 mg b.d. + metron idazole 500 mg b.d. (OCM). H. pylori was assessed by CLO-test and histology before and 4 weeks after therapy. Antibiotic resistance was assessed by E- test. Results: On intention-to-treat analysis RCM was more effective than OCM (84 % vs. 69%; P < 0.03) and BAM (84% vs. 63%; P < 0.004). MIC determination wa s successful in 117 out of 210 patients (55%); metronidazole resistance was present in 52 out of 117 patients (44%) and clarithromycin resistance was present in 17 out of 117 patients (14%). Excellent cure rates were achieved when strains were sensitive to both antibiotics (100% with RCM and BAM and 90% with OCM), whereas RCM was superior to OCM (P=0.009) and BAM (P=0.001) with respect to overall resistant strains (94% vs. 57% and 38%, respective ly). Conclusions: One-week RCM is the best regimen to eradicate H. pylori in our geographical area. This seems to be linked to the better ability of RCM co mpared to OCM and BAM in overcoming the high prevalence of H. pylori resist ance to both metronidazole and clarithromycin in our region.