Antimicrobial treatment of Helicobacter pylori infection.

Helicobacter pylori is susceptible to many antimicrobials, but clinically only a few are effective. Two antimicrobials with bismuth or ranitidine or a proton pump inhibitor such as omeprazole are required to achieve a cure rate of >90% and to avoid resistance, which occurs when clarithromycin or metronidazole is the single antimicrobial used. Bismuth plus metronidazole and tetracycline is effective but causes more side effects than does treatment with omeprazole, amoxicillin, and clarithromycin; metronidazole can replace clarithromycin. To ensure a high cure rate, treatment is required for 10 days, but 7-day regimens have sometimes been as successful. A course of ranitidine bismuth citrate for 28 days, given with clarithromycin for the first 14 days, cures 80%-85% of patients, but given with amoxicillin it cures only 74%. In developing countries resistance to metronidazole can reach 95%. An inexpensive regimen is bismuth subsalicylate (two tablets) plus furazolidone (100 mg), four times daily for 4 weeks; however, as this yields a cure rate of only 72%, this regimen is not truly cost-effective.