title: A new eradication resistance index as a predictor of metronidazole-containing second-line treatment of Helicobacter pylori.
abstract: BACKGROUND
  It is helpful in clinical practice to predict the effects of eradication therapy on Helicobacter pylori.
  
  
  OBJECTIVE
  To develop a useful predictor of the response to metronidazole (MNZ)-containing second-line regimens by combining minimal inhibitory concentrations (MICs) of both amoxicillin (AMX) and MNZ, and the results of urea breath test (UBT) before the treatment.
  
  
  METHODS
  We enrolled 107 patients who showed eradication failure following first-line triple therapy with a proton pump inhibitor, AMX and clarithromycin. The eradication resistance index was defined as: [pre-treatment UBT result ( per thousand)] x [AMX MIC (microg/ml)] x [MNZ MIC (microg/ml)]. Second-line eradication therapy with lansoprazole, AMX and MNZ was administered for 1 week. Eradication was confirmed by the UBT.
  
  
  RESULTS
  The eradication resistance index in subjects showing eradication failure and those showing successful eradication was 9.72 +/- 6.63 and 1.25 +/- 2.31, respectively (p < 0.001). When a cutoff value of 3 was used, the eradication resistance index predicted the response to therapy with a specificity of 93.8%, sensitivity of 81.8%, and accuracy of 92.5%.
  
  
  CONCLUSIONS
  The eradication resistance index is a more useful predictor of response to MNZ-containing regimens for second-line treatment than only pretreatment UBT results or MNZ resistance.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Nishizawa
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Masaoka
authors.forename: Eisuke
authors.initials: E
authors.lastname: Iwasaki
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Hibi
mesh_terms: D000368:Aged; D000658:Amoxicillin / Q000494:pharmacology / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001944:Breath Tests; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000187:drug effects*; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000494:pharmacology / Q000627:therapeutic use*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D017211:Treatment Failure; D014508:Urea / Q000032:analysis
chemical_list: D000890:Anti-Infective Agents; D008795:Metronidazole; D000658:Amoxicillin; D014508:Urea