title: Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome. a double-blind, randomized, placebo-controlled study.
abstract: OBJECTIVE
  We have recently found an association between abnormal lactulose breath test (LBT) findings and irritable bowel syndrome (IBS). The current study was designed to test the effect of antibiotic treatment for IBS in a double-blind fashion.
  
  
  METHODS
  Consecutive IBS subjects underwent an LBT with the results blinded. All subjects were subsequently randomized into two treatment groups (neomycin or placebo). The prevalence of abnormal LBT was compared with a gender-matched control group. Seven days after completion of treatment, subjects returned for repeat LBT. A symptom questionnaire was administered on both days.
  
  
  RESULTS
  After exclusion criteria were met, 111 IBS subjects (55 neomycin, 56 placebo) entered the study, with 84% having an abnormal LBT, compared with 20% in healthy controls (p < 0.01). In an intention-to-treat analysis of all 111 subjects, neomycin resulted in a 35.0% improvement in a composite score, compared with 11.4% for placebo (p < 0.05). Additionally, patients reported a percent bowel normalization of 35.3% after neomycin, compared with 13.9% for placebo (p < 0.001). There was a graded response to treatment, such that the best outcome was observed if neomycin was successful in normalizing the LBT (75% improvement) (one-way ANOVA, p < 0.0001). LBT gas production was associated with IBS subgroup, such that methane excretion was 100% associated with constipation-predominant IBS. Methane excretors had a mean constipation severity of 4.1, compared with 2.3 in all other subjects (p < 0.001).
  
  
  CONCLUSIONS
  An abnormal LBT is common in subjects with IBS. Normalization of LBT with neomycin leads to a significant reduction in IBS symptoms. The type of gas seen on LBT is also associated with IBS subgroup.
authors.affiliation: GI Motility Program, Department of Medicine, CSMC Burns and Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Pimentel
authors.forename: Evelyn J
authors.initials: EJ
authors.lastname: Chow
authors.forename: Henry C
authors.initials: HC
authors.lastname: Lin
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001944:Breath Tests; D016022:Case-Control Studies; D003109:Colonic Diseases, Functional / Q000175:diagnosis* / Q000188:drug therapy; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007792:Lactulose; D008297:Male; D009355:Neomycin / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D007792:Lactulose; D009355:Neomycin