title: Helicobacter pylori resistance to metronidazole and clarithromycin in Ireland.
abstract: BACKGROUND
  Helicobacter pylori eradication rates have fallen considerably in recent years. Antibiotic resistance is thought to be rising.
  
  
  OBJECTIVE
  To examine the levels of resistance to metronidazole (MTZ) and clarithromycin (CLA) in H. pylori, isolates were taken in a reference centre in Ireland from 2007 to 2008 and were compared to a similar cohort from a study in 1997.
  
  
  METHODS
  Antimicrobial susceptibilities were tested by E-test. Frequencies of spontaneous metronidazole and clarithromycin resistance were measured on an agar plate containing the antibiotics at concentrations of 2x and 4x minimum inhibition concentration values. Clinical data were obtained from charts, laboratory and endoscopy reports.
  
  
  RESULTS
  Two hundred and twenty-two patients were analyzed, 98 were females. Colonies amenable to culture were grown in 219 patients. Thirty-seven had prior attempts at eradication therapy (all with amoxicillin-CLA-proton pump inhibitor. A total of 31.5% of the patients had strains resistant to MTZ and 13.2% of the patients were noted to have strains resistant to CLA. About 8.6% of the patients had strains resistant to both the agents. CLA resistance was 9.3% in those who had no prior eradication therapy compared with 32.4% of those who had. CLA resistance increased from 3.9%, among treatment-naive patients in 1997, to 9.3% in our study. MTZ resistance was 29.1% in the treatment-naive population. In 1997, MTZ resistance in the treatment-naive cohort was 27.1%. MTZ resistance was more likely to occur in females (35.4 vs. 28.5%) than in males.
  
  
  CONCLUSIONS
  This study shows that resistance to CLA among Irish patients infected with H. pylori has increased since 1997. The future of treatment may well lie in the widespread use of sensitivity testing before the treatment. This would promote an accurate treatment.
authors.affiliation: Deparment of Gastroenterology, Adelaide and Meath Hospital incorporating the National Children's Hospital/Trinity College Dublin, Dublin, Ireland. jpanthonyoconnor@hotmail.com
authors.forename: Anthony
authors.initials: A
authors.lastname: O'connor
authors.forename: Ikue
authors.initials: I
authors.lastname: Taneike
authors.forename: Abdurrazag
authors.initials: A
authors.lastname: Nami
authors.forename: Niamh
authors.initials: N
authors.lastname: Fitzgerald
authors.forename: Philip
authors.initials: P
authors.lastname: Murphy
authors.forename: Barbara
authors.initials: B
authors.lastname: Ryan
authors.forename: Humphrey
authors.initials: H
authors.lastname: O'connor
authors.forename: Asghar
authors.initials: A
authors.lastname: Qasim
authors.forename: Niall
authors.initials: N
authors.lastname: Breslin
authors.forename: Colm
authors.initials: C
authors.lastname: O'moráin
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001706:Biopsy; D017291:Clarithromycin / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D005260:Female; D005756:Gastritis / Q000188:drug therapy / Q000453:epidemiology / Q000473:pathology; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use*; D008875:Middle Aged; D015995:Prevalence
chemical_list: D000900:Anti-Bacterial Agents; D008795:Metronidazole; D017291:Clarithromycin