title: The relationship between consumption of antimicrobial agents and the prevalence of primary Helicobacter pylori resistance.
abstract: BACKGROUND
  Primary and acquired resistance to the antimicrobial agents is a primary reason for the failure of Helicobacter pylori eradication therapies. We assessed the primary antibiotic resistance rates of H. pylori to three different antibiotics and its relationship due to the annual antibiotic consumption in Japan during the period prior to approval of anti-H. pylori therapy in Japan.
  
  
  METHODS
  Antibiotic susceptibility was tested using the agar dilution method for clarithromycin, amoxicillin and metronidazole. Isolates were considered resistant when the MIC value was > 8 mg/l for metronidazole, > 1 mg/l for clarithromycin and < 0.5 mg/l for amoxicillin.
  
  
  RESULTS
  Helicobacter pylori isolates were obtained from 593 Japanese patients from 1995 to 2000. Primary resistance of H. pylori to clarithromycin, metronidazole and amoxicillin was found in 11%, 9% and 0.3% strains, respectively. The proportion with clarithromycin resistance significantly increased from 7% in 1997-98 to 15.2% in 1999-2000 (p =.003). During the same period the metronidazole resistance rate also increased from 6.6% in 1997-98 to 12% in 1999-2000 (p =.02). The prevalence of clarithromycin and metronidazole was related to the annual consumption of these antimicrobial agents.
  
  
  CONCLUSIONS
  Resistance rates for both clarithromycin and metronidazole appear to reflect the annual consumption of these agents. The high rate of clarithromycin resistance in Japan suggests that the effectiveness of clarithromycin-based therapies may be compromised in the near future.
authors.affiliation: Department of Endoscopy, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: L
authors.initials: L
authors.lastname: Perez Aldana
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: S
authors.initials: S
authors.lastname: Nakagawa
authors.forename: M
authors.initials: M
authors.lastname: Kawarasaki
authors.forename: T
authors.initials: T
authors.lastname: Nagasako
authors.forename: T
authors.initials: T
authors.lastname: Mizushima
authors.forename: H
authors.initials: H
authors.lastname: Oda
authors.forename: J
authors.initials: J
authors.lastname: Kodaira
authors.forename: Y
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Y
authors.initials: Y
authors.lastname: Komatsu
authors.forename: R
authors.initials: R
authors.lastname: Zheng
authors.forename: H
authors.initials: H
authors.lastname: Takeda
authors.forename: T
authors.initials: T
authors.lastname: Sugiyama
authors.forename: M
authors.initials: M
authors.lastname: Asaka
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017291:Clarithromycin / Q000494:pharmacology / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy / Q000453:epidemiology*; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000494:pharmacology / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests; D015995:Prevalence
chemical_list: D000900:Anti-Bacterial Agents; D008795:Metronidazole; D017291:Clarithromycin