Impact of clarithromycin resistance on the effectiveness of a regimen for Helicobacter pylori: a prospective study of 1-week lansoprazole, amoxycillin and clarithromycin in active peptic ulcer

Aliment Pharmacol Ther. 1999 Jun;13(6):775-80. doi: 10.1046/j.1365-2036.1999.00549.x.


Background: Clarithromycin is a key antimicrobial in the combinations used to cure Helicobacter pylori infections, so there is a need to define the impact of in vitro resistance on in vivo results.

Methods: A prospective trial was designed to study the effectiveness of the 1-week combination of lansoprazole, clarithromycin and amoxycillin in 102 consecutive patients with active peptic ulcer. The pre-treatment and post-treatment sensitivity to amoxycillin, metronidazole and clarithromycin were studied by E-test, and H. pylori status was defined by histology, culture and urease test at diagnosis and one month after treatment, and by urea-breath test 2 months after treatment.

Results: The eradication rate (intention-to-treat analysis) was 77% (95% CI: 69-86). No clinical factor was found to be different between eradicated and non-eradicated patients. Clarithromycin-resistant strains were found in 10 (10%; CI: 5-17) patients. The eradication rate was 20% (CI: 3-56) in these patients vs. 83% (CI: 75-91) in patients harbouring clarithromycin-sensitive strains (P < 0.001). A logistic-regression analysis confirmed clarithromycin resistance as the only factor associated with treatment failure.

Conclusions: Clarithromycin resistance significatively impairs the effectiveness of the combination of lansoprazole, amoxycillin, and clarithromycin. The 80% efficacy goal will be difficult to reach in areas with high (>10%) primary clarithromyicin resistance, if currently recommended proton pump inhibitor-triple therapies are used.

MeSH terms

  • 2-Pyridinylmethylsulfinylbenzimidazoles
  • Adult
  • Aged
  • Amoxicillin / administration & dosage*
  • Clarithromycin / administration & dosage*
  • Drug Resistance, Microbial
  • Female
  • Helicobacter Infections / drug therapy*
  • Helicobacter pylori / drug effects*
  • Humans
  • Lansoprazole
  • Male
  • Middle Aged
  • Omeprazole / administration & dosage
  • Omeprazole / analogs & derivatives*
  • Peptic Ulcer / drug therapy*
  • Prospective Studies


  • 2-Pyridinylmethylsulfinylbenzimidazoles
  • Lansoprazole
  • Amoxicillin
  • Clarithromycin
  • Omeprazole