title: Impact of Helicobacter pylori resistance to clarithromycin on the efficacy of the omeprazole-amoxicillin-clarithromycin therapy.
abstract: 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.
  
  
  OBJECTIVE
  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.
authors.affiliation: Service de Bactériologie-Virologie, Hôpital Henri-Mondor, Créteil, France. jacques.tankovic@sat.ap-hop-paris.fr
authors.forename: J
authors.initials: J
authors.lastname: Tankovic
authors.forename: D
authors.initials: D
authors.lastname: Lamarque
authors.forename: C
authors.initials: C
authors.lastname: Lascols
authors.forename: C J
authors.initials: CJ
authors.lastname: Soussy
authors.forename: J C
authors.initials: JC
authors.lastname: Delchier
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000494:pharmacology* / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001944:Breath Tests; D017291:Clarithromycin / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis*; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005838:Genotype; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000494:pharmacology* / Q000627:therapeutic use; D010406:Penicillins / Q000494:pharmacology* / Q000627:therapeutic use; D016133:Polymerase Chain Reaction; D054328:Proton Pump Inhibitors
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004791:Enzyme Inhibitors; D010406:Penicillins; D054328:Proton Pump Inhibitors; D000658:Amoxicillin; D017291:Clarithromycin; D009853:Omeprazole