There is limited knowledge about the association between the composition of the intestinal microbiota and clinical features of irritable bowel syndrome (IBS).
Dr Muriel Derrien and colleagues from France collected information on the fecal and mucosa-associated microbiota of patients with IBS, and evaluated whether these were associated with symptoms.
The researchers collected fecal and mucosal samples from adult patients who met the Rome III criteria for IBS at a secondary/tertiary care outpatient clinics in Sweden, as well as from healthy subjects.
The exploratory set comprized 149 subjects, 232 fecal samples and 59 mucosal biopsy samples were collected and analyzed by 16S ribosomal RNA targeted pyrosequencing.
|Fecal microbiota showed covariation with mucosal adherent microbiota|
The team reported that the validation set comprized 46 subjects, 46 fecal samples, but no mucosal samples.
For each subject, the researchers measured exhaled H2 and CH4, oro-anal transit time, and the severity of psychological and gastrointestinal symptoms.
The researchers measured fecal methanogens by quantitative polymerase chain reaction.
Numerical ecology analyses and a machine learning procedure were used to analyze the data.
The team observed that fecal microbiota showed covariation with mucosal adherent microbiota.
The research team found no differences in fecal microbiota abundance or composition between patients with IBS vs healthy patients.
A machine learning procedure, a computational statistical technique, allowed us to reduce the 16S ribosomal RNA data complexity into a microbial signature for severe IBS, consisting of 90 bacterial operational taxonomic units.
The team confirmed the robustness of the intestinal microbial signature for severe IBS in the validation set.
The signature was able to discriminate between patients with severe symptoms, patients with mild/moderate symptoms, and healthy subjects.
By using this intestinal microbiota signature, the researchers found IBS symptom severity to be associated negatively with microbial richness, exhaled CH4, presence of methanogens, and enterotypes enriched with Clostridiales or Prevotella species.
This microbiota signature could not be explained by differences in diet or use of medications.
Dr Derrien's team concludes, "In analyzing fecal and mucosal microbiota from patients with IBS and healthy individuals, we identified an intestinal microbiota profile that is associated with the severity of IBS symptoms."