title: Lactulose breath test results in patients with persistent abdominal symptoms following Giardia lamblia infection.
abstract: OBJECTIVE
  Bacterial overgrowth has been implicated in the pathogenesis of irritable bowel syndrome (IBS). The objective of this study was to investigate whether post-infectious IBS following Giardia lamblia infection is related to intestinal bacterial overgrowth, as diagnosed by the lactulose breath test (LBT).
  
  
  METHODS
  Seventy-seven patients with persistent gastrointestinal complaints related to a recent outbreak of G. lamblia infection were included in the study. Despite one or several courses of treatment with metronidazole during the previous months, 23 of the patients were still stool positive for G. lamblia, whereas the remaining 54 patients had cleared the infection. All patients and 42 healthy volunteers underwent a LBT with 10 g lactulose, and their customary and post-LBT abdominal symptoms were scored.
  
  
  RESULTS
  Ninety-five percent of the patients had IBS. Lactulose-induced hydrogen breath excretion was not significantly different in patients and controls. Customary and post-LBT symptoms were abnormally high in the patients, irrespective of both G. lamblia infection status and LBT results. Furthermore, lactulose challenge replicated the patients' customary complaints in 70% of the patients.
  
  
  CONCLUSIONS
  Gastrointestinal complaints in patients with persistent or cleared giardiasis were unrelated to hydrogen breath excretion after lactulose challenge. Post-giardiasis IBS cannot be ascribed to intestinal bacterial overgrowth, as diagnosed by LBT.
authors.affiliation: Department of Nutrition and Department of Medicine, Haukeland University Hospital, Bergen, Norway. mette.morken@helse.bergen.no
authors.forename: Mette H
authors.initials: MH
authors.lastname: Morken
authors.forename: Gunnar
authors.initials: G
authors.lastname: Nysaeter
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Strand
authors.forename: Trygve
authors.initials: T
authors.lastname: Hausken
authors.forename: Arnold
authors.initials: A
authors.lastname: Berstad
mesh_terms: D015746:Abdominal Pain / Q000139:chemically induced / Q000382:microbiology / Q000469:parasitology; D000293:Adolescent; D000328:Adult; D000818:Animals; D000981:Antiprotozoal Agents / Q000627:therapeutic use; D001944:Breath Tests; D005260:Female; D016829:Giardia lamblia; D005873:Giardiasis / Q000150:complications* / Q000188:drug therapy; D006801:Humans; D006859:Hydrogen / Q000378:metabolism; D007422:Intestines / Q000382:microbiology; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000382:microbiology / Q000469:parasitology; D007792:Lactulose / Q000009:adverse effects; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use; D008875:Middle Aged
chemical_list: D000981:Antiprotozoal Agents; D008795:Metronidazole; D007792:Lactulose; D006859:Hydrogen