title: Clarithromycin-resistant Helicobacter pylori in patients with duodenal ulcer in the United States.
abstract: BACKGROUND
  Clarithromycin is a key component of several antimicrobial treatment regimens for Helicobacter pylori. Cure rates with clarithromycin-containing regimens are significantly decreased when resistance is present. Resistance develops by a point mutation in the ribosomal RNA of some organisms exposed to clarithromycin. We studied the prevalence of clarithromycin-resistant organisms in patients with duodenal ulcer in the United States from 1993-96.
  
  
  METHODS
  Patients with endoscopic evidence of a duodenal ulcer were studied. Gastric biopsies were cultured for H. pylori and antimicrobial sensitivity was determined by the E-test (epsilometer agar diffusion gradient).
  
  
  RESULTS
  In 1993-94, three of 78 patients (4%) had clarithromycin-resistant strains of H. pylori. In 1995-96, 44 of 348 patients (12.6%; p = 0.025) had resistant strains of H. pylori. Patients who had previously failed antimicrobial treatment for H. pylori accounted for much of the increase in resistant strains (25%).
  
  
  CONCLUSIONS
  Failed therapy with clarithromycin-based regimens is a growing cause of antimicrobial resistance in H. pylori in the United States. Whereas the overall rates of primary resistance are low, the increase in secondary resistance over a short period of time is worrisome. New treatments that prevent the emergence of resistance may be important in the future.
authors.affiliation: University of Wisconsin Medical School, Milwaukee 53233, USA.
authors.forename: N
authors.initials: N
authors.lastname: Vakil
authors.forename: B
authors.initials: B
authors.lastname: Hahn
authors.forename: D
authors.initials: D
authors.lastname: McSorley
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D017291:Clarithromycin / Q000627:therapeutic use*; D004352:Drug Resistance, Microbial; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D000900:Anti-Bacterial Agents; D017291:Clarithromycin