Structural changes in the gut microbiome of constipated patients.

Previous studies using culture-based methods suggested an association between constipation and altered abundance of certain taxa of the colonic microbiome. We aim to examine the global changes in gut microbial composition of constipated patients. A cross-sectional pilot study using 16S rRNA gene pyrosequencing was performed to compare stool microbial composition of eight constipated patients and 14 nonconstipated controls. Only obese children were enrolled so that the microbiome features associated with constipation would not be obscured by those associated with obesity. The sequencing reads were processed by QIIME for quantitative analysis of the microbial composition at genus and above levels. Dietary intake for all the individuals was assessed by dietary recalls and a food frequency questionnaire. The ecological diversities of fecal microbiome of the constipated patients differed from those of the controls. Significantly decreased abundance in Prevotella and increased representation in several genera of Firmicutes were observed in constipated patients compared with controls. The conventional probiotic genera Lactobacillus and Bifidobacteria were not decreased in the microbiomes of the constipated patients. These alterations in the fecal microbiome of constipated patients suggested that a novel probiotic treatment including certain Prevotella strains may be more effective than conventional probiotic products incorporating Lactobacillus or Bifidobacterium species. While it is possible that the observed changes in the microbiome in constipated subjects are a consequence of a low-fiber diet, these changes also predict a different pattern of bacterial fermentation end-products, such as increased butyrate production, which may contribute to pathogenesis of constipation.