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Crohn's disease

A long-term inflammatory bowel disease that can affect any part of the gut.

Compared within 8 studies that had both: 1,313 people with Crohn's and 728 healthy people. 161 microbes are less common in people with Crohn's, and 35 more common.

A difference is an association: it doesn’t mean these microbes cause, prevent or treat Crohn's.

Phylum

Searching opens both lists and shows only matching rows.

Less common in Crohn's · 161

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Gallintestinimicrobium propionicum in 8 studies Healthy 73% Crohn's 37%
  2. Clostridium sp. AM49-4BH in 8 studies Healthy 44% Crohn's 12%
  3. Alistipes shahii in 8 studies Healthy 63% Crohn's 28%
  4. Gemmiger formicilis in 8 studies Healthy 63% Crohn's 28%
  5. Oscillospiraceae bacterium in 8 studies Healthy 34% Crohn's 7.8%

More common in Crohn's · 35

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Faecalimonas umbilicata in 8 studies Healthy 8.3% Crohn's 27%
  2. Dialister pneumosintes in 8 studies Healthy under 1% Crohn's 7.7%
  3. Enterocloster clostridioformis in 8 studies Healthy 18% Crohn's 34%
  4. Thomasclavelia ramosa in 8 studies Healthy 16% Crohn's 32%
  5. Enterocloster aldenensis in 8 studies Healthy 20% Crohn's 37%

Where these numbers come from

Studies
Only GMrepo projects that had people with the condition and healthy people, 10 or more of each. Numbers come from those studies, never from pooling.Sampled in Canada, China, Germany, Ireland, the United States.
How common
The share of people whose sample has any of it, in the people with the condition and in the healthy people of those same studies. Tested within studies (Cochran–Mantel–Haenszel, corrected for testing many microbes); a difference counts when it is clear and meaningful (Cohen’s h of 0.2 or more).
Strength word
Counted by code from how many studies point the same way: Seen again and again (3 or more, none clearly the other way), Seen more than once (2, the majority), Seen once (1, listed last). Where studies disagree, a row isn’t listed.
Each study
Tap a row for every study’s own numbers, and for how much carriers have.
Analysis
Our analysis of GMrepo data. GMrepo on Data sources · Read the rules

Also compared · 481 microbes

Compared within studies that had both, but not listed above.

Studies disagree · 51

No meaningful difference · 430
PubMed · human studies and reviews first

Recent research

All research on it
  1. Clinical trial Nature communications · 2026
    Fecal microbiota transplantation for the decolonization of mucosal adherent-invasive Escherichia coli in Crohn's disease: an open-label pilot study.
    PubMed ↗
  2. Observational Journal of pediatric gastroenterology and nutrition · 2026
    Gut microbiome in pediatric acute pancreatitis and Crohn's disease versus irritable bowel syndrome and healthy controls.
    PubMed ↗
  3. Observational Gut and liver · 2026
    Age-Related Microbial Differences in Newly Diagnosed Crohn's Disease Reveal the Distinct Enrichment of Oral-Associated Taxa in Pediatric Patients.
    PubMed ↗
  4. Systematic review BMC gastroenterology · 2026
    Specific alterations in the gut microbiome and metabolome across disease locations of Crohn's disease: a systematic review.
    PubMed ↗
  5. Review Journal of bacteriology · 2026
    Escherichia coli pathobionts and Crohn's disease: varied genetic paths leading to similar phenotypes.
    PubMed ↗

Source: PubMed, U.S. National Library of Medicine · 164 linked papers, last 10 years