Intestinal Biofilms are an endoscopic Feature of Irretable Bowel Syndrome

Background:

IBS is a multifactorial disorder with potential involvement of the gut microbiome. Recently, biofilms have been implicated in a variety of GI-diseases (Tytgat, Trends in Microbiology, 2018).

Methods:

Endoscopically-visible biofilms were defined as cohesive layer on the intestinal surface, which either resist detachment by jet-washing or detach in a film-like manner. The presence of biofilms was scored prospectively at the Vienna General Hospital between May and August 2018 (n = 446 cases). Cases with a BBPS < 6 (n = 43), with non-PEG-based cleansing (n = 9), or with cecum not reached (n = 9) were excluded from the analysis. Mucosal/biofilm-biopsies were collected from patients (n = 24) and controls (n = 33) and subjected to scanning electron microscopy (SEM), fluorescence in situ hybridization (FISH) and Next-generation-sequencing.

Results:

Biofilms were most prevalent in IBS (Table) and were located in the cecum (72%), terminal ileum (62%), ascending colon (44%) and proximal colon (9%). Ileal biofilms concurred with right-sided-colonic biofilms in 78%. Two out of three patients kept their biofilm phenotype upon a follow-up colonoscopy. Bacterial origin of biofilms was validated by 16S-sequencing, FISH and SEM. 16S-analysis showed a reduced bacterial diversity and increased abundance of Bacteroides and E. coli in biofilms. FISH and SEM revealed a dense bacterial aggregate in contact with the intestinal epithelium with a thickness of up to 15 µm. Bacterial composition was similar in biofilm biopsies and flushes and distinct from normal mucosa.

Tab. 1

Diagnosis	n	Intestinal-Biofilm	% positive
total	385	61	16
IBS	36	17	47
post-transplant	15	6	40
ulcerative colitis	45	12	27
liver cirrhosis	26	5	19
polyps	103	12	12
GI-malignancy	27	3	11
healthy	27	3	11
diverticulosis	59	6	10
Crohn's disease	52	3	6

Discussion:

In this tertiary teaching hospital cohort, endoscopically-visible biofilms are a characteristic feature of patients with IBS, UC and after transplantation and likely caused by dysbiosis (due to previous infection, antibiotic- and/or immunosuppressive therapies). We speculate that intestinal biofilms are causatively involved in the pathogenesis of IBS as they may explain common IBS symptoms such as small intestinal bacterial overgrowth, bile acid diarrhea, distension pain or bloating.