title: Antibiotic resistance of Helicobacter pylori in Mazandaran, North of Iran.
abstract: BACKGROUND
  The aim of this study was to investigate the prevalence of resistances in Helicobacter pylori against commonly used antibiotics including metronidazole, clarithromycin, amoxicillin, and tetracycline in Iranian patients.
  
  
  METHODS
  H. pylori isolates were collected from gastric biopsies from patients referred for upper gastrointestinal endoscopy at Tooba Medical Center, Sari, Iran, from 2007 to 2010. None of them had been using antibiotics for at least 8 months. H. pylori was identified based on morphological shape and positive biochemical tests for catalase, oxidase, and urease activity. Antibiotic resistance for metronidazole, clarithromycin, amoxicillin, and tetracycline was investigated by using epsilometer test. Resistance was defined by minimal inhibitory concentration (MIC) > 0.5 mg/L for amoxicillin (AMX), >4 mg/L for tetracycline (TET), >8 mg/L for metronidazole (MTZ), and >1 mg/L for clarithromycin (CLR).
  
  
  RESULTS
  Strains were collected from 132 patients, mean age 45.8 years, 52 (39%) were women. Patients had diverse diagnoses: gastritis 42 (31.8%), duodenal ulcer 45 (34%), gastric cancer 15 (11.3%), or gastric ulcer 30 (22.7%). The prevalences of resistance of H. pylori strains isolated from the patients were 73.4% for metronidazole, 30% for clarithromycin, 6.8% for amoxicillin, and 9% for tetracycline. Twenty-eight (21.2%) were double resistant to MTZ-CLR, 16 (12.1%) showed triple resistance to MTZ-CLR-AMX, and 8 (6%) were resistant to all four tested antibiotics (MTZ-CLR-AMX-TET). No associations were detected between multiple resistant strains and clinical manifestations (p > .05).
  
  
  CONCLUSIONS
  The prevalence of H. pylori antibiotic resistance to metronidazole and clarithromycin was high in Iran consistent with the reported low success rates for H. pylori treatment in this country.
authors.affiliation: Department of Bacteriology Tehran, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Talebi Bezmin Abadi
authors.forename: Ashraf M
authors.initials: AM
authors.lastname: Mobarez
authors.forename: Tarang
authors.initials: T
authors.lastname: Taghvaei
authors.forename: Lutz
authors.initials: L
authors.lastname: Wolfram
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000494:pharmacology; D017291:Clarithromycin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D007492:Iran; D008297:Male; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D013752:Tetracycline / Q000494:pharmacology; D055815:Young Adult
chemical_list: D008795:Metronidazole; D000658:Amoxicillin; D013752:Tetracycline; D017291:Clarithromycin