title: Antibiotic resistance in Helicobacter pylori strains and its effect on H. pylori eradication rates in a single center in Korea.
abstract: BACKGROUND
  Clarithromycin, amoxicillin, metronidazole, tetracycline, and levofloxacin have been commonly used for the eradication of Helicobacter pylori. We compared the change in antibiotic resistance of H. pylori strains during two separate periods and investigated the effect of antibiotic resistance on H. pylori eradication.
  
  
  METHODS
  H. pylori strains were isolated from 71 patients between 2009 and 2010 and from 94 patients between 2011 and 2012. The distribution of minimal inhibitory concentration (MIC) of 5 antibiotics was assessed using the agar dilution method, and H. pylori eradication based on the antimicrobial susceptibility of the isolates was investigated retrospectively.
  
  
  RESULTS
  Antibiotic resistance rate against clarithromycin, amoxicillin, tetracycline, metronidazole, and levofloxacin for the 2009-2010 isolates were 7.0% (5/71), 2.8% (2/71), 0% (0/71), 45.1% (32/71), and 26.8% (19/71), respectively, and for the 2011-2012 isolates were 16.0% (15/94), 2.1% (2/94), 0% (0/94), 56.3% (53/94), and 22.3% (21/94), respectively. Multi-drug resistance for 2 or more antibiotics increased slightly from 16.9% (12/71) in the 2009-2010 isolates to 23.4% (22/94) in the 2011-2012 isolates. In follow-up testing of 66 patients, first-line treatment successfully eradicated H. pylori in 50 patients (75.8%) and failed in 4 of 7 patients (57.1%) in a clarithromycin-resistant and amoxicillin-susceptible group.
  
  
  CONCLUSIONS
  We observed an increase in resistance to clarithromycin and an overall increase in multi-drug resistance during the 2 study periods. The effectiveness of the eradication regimen was low with combinations of clarithromycin and amoxicillin, particularly in the clarithromycin-resistant group. Thus, eradication of H. pylori depends upon periodic monitoring of antimicrobial susceptibility.
authors.affiliation: Department of Laboratory Medicine, Yongin Severance Hospital, Yongin, Korea.
authors.forename: Byoungrak
authors.initials: B
authors.lastname: An
authors.forename: Byung Soo
authors.initials: BS
authors.lastname: Moon
authors.forename: Heejung
authors.initials: H
authors.lastname: Kim
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Lim
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Lee
authors.forename: Gyusang
authors.initials: G
authors.lastname: Lee
authors.forename: Sa-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Min
authors.initials: M
authors.lastname: Park
authors.forename: Jong Bae
authors.initials: JB
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010437:Peptic Ulcer / Q000175:diagnosis / Q000382:microbiology; D056910:Republic of Korea; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic resistance; Eradication; Helicobacter pylori