TOPLINE

In laboratory models, gut microbial communities from patients with ulcerative colitis (UC) were more prone to Clostridioides difficile colonization than those from healthy donors, but adding the prebiotic fiber inulin before exposing the cultures to C difficile reduced colonization. Inulin also raised the levels of short-chain fatty acids such as butyrate, possibly helping explain these findings.

METHODOLOGY

• Patients with UC lose some of the gut microbiome's ability to resist colonization by pathogens such as C difficile, which is linked to more severe disease. Microbiome dysfunction also persists after anti-inflammatory treatment. Earlier studies suggested that dietary fibers, including inulin, may help protect against C difficile colonization.
• In this in vitro study, researchers collected fecal samples from patients with UC and healthy donors who had not taken antibiotics in the previous 3 months to identify microbiome features linked to C difficile susceptibility in UC.
• Samples were grown in "mini colons," a miniature bioreactor array designed to mimic the distal colon, with anaerobic conditions and continuous peristaltic flow of nutrient media.
• The team added C difficile to the cultures to see which microbiomes resisted colonization and subsequently analyzed the microbial communities using 16S rRNA sequencing and the metabolites using liquid chromatography-mass spectrometry.
• In cultures derived from some patients with UC, the researchers raised the inulin concentration 10-fold before exposing the cultures to C difficile.

TAKEAWAY

• Susceptibility to colonization was greater among patients with UC than among healthy donors (P < .05).
• Microbiomes that allowed C difficile to colonize (susceptible) differed in overall composition from those that resisted colonization, with lower abundances of Collinsella (P = .007) and Lachnoclostridium (P = .001); fecal alpha diversity was similar between the susceptible and resistant microbial culture groups.
• Compared with resistant cultures, susceptible cultures had lower levels of 3-hydroxybutyrate and higher levels of deoxycholic acid.
• Higher inulin levels reduced C difficile colonization in UC cultures. Inulin also raised the levels of short-chain fatty acids, including butyrate, a fatty acid that previous studies have associated with slower growth of the pathogen.

IN PRACTICE

"The addition of inulin increased colonization resistance, indicating that the taxa needed for resistance may be present but at low levels without prebiotic support," wrote the authors of the study.

SOURCE

The study was led by Kira L. Newman, MD, PhD, University of Michigan, Ann Arbor. It was presented at the American College of Gastroenterology (ACG) 2026 Annual Scientific Meeting in Nashville, Tennessee.

LIMITATIONS

The abstract did not mention any limitations explicitly.

DISCLOSURES

Two authors reported receiving grant or research support from certain pharmaceutical companies or serving as consultants or members of their advisory committees or boards.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.