Neurogastroenterol Motil. 2024 Sep;36(9):e14854. doi: 10.1111/nmo.14854. Epub 2024 Jun 30.

Erica Sande Teige ^1 2, Eline Margrete Randulff Hillestad ^1 2, Elisabeth Kjelsvik Steinsvik ², Ingeborg Brønstad ², Arvid Lundervold ^3 4, Astri J Lundervold ⁵, Jørgen Valeur ^6 7, Trygve Hausken ^1 2, Birgitte Berentsen ², Gülen Arslan Lied ^1 2

Author information

¹Centre for Nutrition, Department of Clinical Medicine, University of Bergen, Bergen, Norway.

²National Centre for Functional Gastrointestinal Disorders, Department of Medicine, Haukeland University Hospital, Bergen, Norway.

³Mohn Medical Imaging and Visualization Centre, Haukeland University Hospital, Bergen, Norway.

⁴Department of Biomedicine, University of Bergen, Bergen, Norway.

⁵Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.

⁶Unger-Vetlesen Institute, Lovisenberg Diaconal Hospital Oslo, Oslo, Norway.

⁷Institute of Clinical Medicine, University of Oslo, Oslo, Norway.

PAbstract

Abstract

Background: The relationship between gut microbiota and irritable bowel syndrome (IBS) subtype is unclear. We aimed to explore whether differences in fecal bacteria composition and short-chain fatty acid (SCFA) levels were associated with subtypes and symptoms of IBS.

Methods: All participants delivered fecal samples and self-reports on IBS Symptom Severity Score (IBS-SSS), Bristol Stool Scale (BSS), and Gastrointestinal Symptom Rating Scale (GSRS). Fecal bacteria composition was assessed by the GA-map® Dysbiosis Test based on 16S rRNA sequences of bacterial species/groups. SCFAs were analyzed by vacuum distillation followed by gas chromatography.

Key results: Sixty patients with IBS were included (mean age 38 years, 46 [77%] females): Twenty-one patients were classified as IBS-D (diarrhea), 31 IBS-M (mixed diarrhea and constipation), and eight IBS-C (constipation). Forty-two healthy controls (HCs) (mean age 35 years, 27 [64%] females) were included. Patients had a significantly higher relative frequency of dysbiosis, lower levels of Actinobacteria, and higher levels of Bacilli than HCs. Eight bacterial markers were significantly different across IBS subgroups and HCs, and 13 bacterial markers were weakly correlated with IBS symptoms. Clostridia and Veillonella spp. had a weak negative correlation with constipation scores (GSRS) and a weak positive correlation with loose stools (BSS). Diarrhea scores (GSRS) and looser stool (BSS) were weakly correlated with levels of total SCFAs, acetic and butyric acid. Levels of total SCFAs and acetic acid were weakly correlated with symptom severity (IBS-SSS).

Conclusions & inferences: Patients with IBS had a different fecal bacteria composition compared to HCs, and alterations of SCFAs may contribute to the subtype.