[Predominance of constipation in subjects with hydrogen-consuming intestinal flora]

There is growing evidence that a disorder in intestinal microbiota would contribute to the development of symptoms in irritable bowel syndrome (IBS) patients. In a subgroup, a remarkably low hydrogen production in lactulose breath test (LBT) is observed. We presume in these patients a predominance of hydrogen consuming gut flora.

[corrected] Describe the clinical presentation of lBS patients with low hydrogen production and to compare their cathartic pattern against those with high hydrogen excretion.

A case-control study was designed. IBS outpatients were included. A validated questionnaire was delivered (IBSSS) in order to assess their symptoms and a LBT was performed. The cathartic pattern was compared between those with low and high hydrogen production on LBT.

One hundred and ten patients were included and 15 of them (13.6%) had low hydrogen production on LBT, which would be compatible with the presence of hydrogen-consuming gut flora. In this group, 11 patients (73.33%) were constipated In contrast, only 30 patients (31.58%) in the high or normal hydrogen production group were constipated [OR 5.95 (95% confidence interval 1.75-20.25; P = 0.03)].

IBS patients with low hydrogen production on lactulose breath test were 6 times more frequently constipated.