title: A study of the methodological and clinical validity of the combined lactulose hydrogen breath test with scintigraphic oro-cecal transit test for diagnosing small intestinal bacterial overgrowth in IBS patients.
abstract: BACKGROUND
  Small intestinal bacterial overgrowth (SIBO) may be a cause of irritable bowel syndrome (IBS); however, current investigations have important limitations. We aimed to identify clinically relevant diagnostic criteria for SIBO based on lactulose hydrogen breath test (LHBT) alone and combined with scintigraphic measurement of oro-cecal transit (SOCT).
  
  
  METHODS
  Results of LHBT/SOCT investigation from 89 IBS patients and 13 healthy volunteers were included in a systematic analysis of six published criteria for SIBO diagnosis. Clinical relevance of competing criteria was determined by assessing (i) prevalence of SIBO in IBS patients and healthy volunteers (ii) if SIBO diagnosis predicted improvement in IBS symptoms in a prospective, pilot therapeutic trial of a non-absorbable antibiotic (rifaximin 600 mg b.d.) in IBS patients.
  
  
  RESULTS
  Reproducibility of SIBO diagnosis by combined LHBT/SOCT was near perfect. A ≥5 ppm H2 increase prior to appearance of cecal contrast was detected in more IBS patients than healthy volunteers (35/89 vs 1/13; p = 0.026), but not for other diagnostic criteria. IBS patients with SIBO, compared to those without SIBO, reported significantly greater improvement in abdominal symptoms following rifaximin therapy (p < 0.002 overall IBS symptom severity). This improvement was most marked in D-IBS patients in whom all symptoms improved, including stool frequency and consistency (all p < 0.004).
  
  
  CONCLUSIONS
  Combined LHBT/SOCT testing using a H2 5 ppm cutoff may identify a subgroup of IBS patients with SIBO. Pilot data examining the clinical response to rifaximin suggest that this subset of IBS patients may benefit more than those with a normal test.
authors.affiliation: Department of Gastroenterology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Division of Gastroenterology & Hepatology, Tongde Hospital of Zhejiang Province, Hangzhou, China.
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: X
authors.initials: X
authors.lastname: Zheng
authors.forename: H
authors.initials: H
authors.lastname: Chu
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: Y
authors.initials: Y
authors.lastname: Cong
authors.forename: M
authors.initials: M
authors.lastname: Fried
authors.forename: M
authors.initials: M
authors.lastname: Fox
authors.forename: N
authors.initials: N
authors.lastname: Dai
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology; D001944:Breath Tests / Q000379:methods; D002432:Cecum / Q000000981:diagnostic imaging*; D005260:Female; D005765:Gastrointestinal Agents; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging / Q000382:microbiology*; D043183:Irritable Bowel Syndrome / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000382:microbiology*; D007792:Lactulose; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012294:Rifamycins / Q000008:administration & dosage / Q000494:pharmacology; D000078262:Rifaximin; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D005765:Gastrointestinal Agents; D012294:Rifamycins; D007792:Lactulose; D000078262:Rifaximin
keywords: antibiotic therapy; irritable bowel syndrome (IBS); lactulose hydrogen breath test (LHBT); rifaximin; scintigraphic oro-cecal transit (SOCT) test; small intestinal bacterial overgrowth (SIBO)