Impact of Helicobacter pylori resistance to clarithromycin on the efficacy of the omeprazole-amoxicillin-clarithromycin therapy

Aliment Pharmacol Ther. 2001 May;15(5):707-13. doi: 10.1046/j.1365-2036.2001.00971.x.


Background: Helicobacter pylori resistance to clarithromycin is relatively frequent in France and is assumed to be the main cause of failure of the proton pump inhibitor-amoxicillin-clarithromycin (proton pump inhibitor-AC) therapy, which is the first-line regimen in France.

Aim: To determine the respective effects of clarithromycin primary and secondary resistances on efficacy of the proton pump inhibitor-AC regimen and to determine whether failures are associated with persistence of the same strain or with emergence of a new one.

Methods: A total of 123 H. pylori-infected patients were treated for 7 days with omeprazole 20 mg b.d., amoxicillin 1 g b.d., and clarithromycin 500 mg b.d. Eradication was assessed by breath test in 102 patients. Minimal inhibitory concentrations of clarithromycin were determined by E-test. Strain genotyping was performed by random amplified polymorphic DNA.

Results: The pre-treatment and post-treatment prevalences of clarithromycin resistance were 19% (23 out of 123) and 69% (nine out of 13), respectively. The rates of eradication were 68% (69 out of 102), 79% (67 out of 85), and 12% (two out of 17) for all, susceptible and resistant strains, respectively. The post-treatment isolate was available for six patients with a susceptible pre-treatment isolate and a persistent infection. Resistance emerged in two patients and was associated with persistence of the pre-treatment strain in one and with selection of a new strain in the other.

Conclusions: In our hospital, failures of the proton pump inhibitor-AC therapy are related to both clarithromycin primary and secondary resistances, but the emergence of secondary resistance does not explain all of the failures in the initial clarithromycin-susceptible group. In that group a new strain can emerge after failure.

MeSH terms

  • Administration, Oral
  • Adolescent
  • Adult
  • Aged
  • Amoxicillin / pharmacology*
  • Amoxicillin / therapeutic use
  • Anti-Bacterial Agents / pharmacology*
  • Breath Tests
  • Clarithromycin / pharmacology*
  • DNA, Bacterial / analysis*
  • Drug Resistance
  • Drug Therapy, Combination
  • Enzyme Inhibitors / pharmacology*
  • Enzyme Inhibitors / therapeutic use
  • Female
  • Genotype
  • Helicobacter Infections / drug therapy*
  • Helicobacter pylori / drug effects*
  • Humans
  • Male
  • Middle Aged
  • Omeprazole / pharmacology*
  • Omeprazole / therapeutic use
  • Penicillins / pharmacology*
  • Penicillins / therapeutic use
  • Polymerase Chain Reaction
  • Proton Pump Inhibitors


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Enzyme Inhibitors
  • Penicillins
  • Proton Pump Inhibitors
  • Amoxicillin
  • Clarithromycin
  • Omeprazole