The name E. coli understandably worries people. But E. coli is a large family of bacteria, and not every type causes food poisoning or an infection.
This page is about AIEC, a particular type of E. coli being studied in Crohn's disease. We do not yet fully understand whether it helps drive inflammation, takes advantage of an already inflamed bowel, or both.
What do we know about AIEC?
AIEC has been found more often in the bowel lining of some people with Crohn's disease. It may be part of the disease in that subgroup, but it is not found in everyone and it is not the single cause of Crohn's disease. Researchers are tracking it because it may be possible to change or remove it.
In this video, I explain why AIEC is interesting, what the earlier AI-assisted antibiotic discovery showed and what researchers are following now. Watch the new video.
What is AIEC?
AIEC stands for adherent-invasive Escherichia coli. The name describes how these bacteria behave: they can stick to cells in the bowel lining and enter them.
That does not mean every E. coli result is AIEC. A standard stool microbiome report cannot reliably identify it because AIEC is defined partly by its behaviour in specialist laboratory testing.
What we know
AIEC is found in some people with Crohn's disease, particularly when the last part of the small bowel is involved.
What we do not know
Whether it starts inflammation, grows because inflammation is already present, or does both.
What researchers are tracking
Whether changing AIEC leads to a meaningful and lasting improvement in Crohn's disease.
The earlier AI-assisted antibiotic discovery
The original version of this page followed a 2025 Nature Microbiology study of enterololin. Researchers screened 10,747 compounds and used artificial intelligence to help understand how the selected compound worked.
In mice carrying AIEC, enterololin reduced the bacterium while leaving much of the wider microbiome alone. That was an interesting proof of concept, but it was not a human Crohn's disease trial. Enterololin is not an available treatment.
What the newer human study adds
A 2026 Nature Communications pilot study looked at whether AIEC in the bowel lining could be changed in people. Thirty adults with Crohn's disease received one faecal microbiota transplant, or FMT, during colonoscopy.
Only eight participants had AIEC in bowel-lining samples at the start and could be assessed afterwards. AIEC was no longer detected in those eight. The study mainly assessed safety and bacterial change over 12 weeks. It was not designed to show whether removing AIEC improves Crohn's symptoms or controls the disease.
What does this mean now?
It tells us that AIEC may be changeable. The next question is whether that change leads to better outcomes that last.
For patients, routine Crohn's care remains based on symptoms, calprotectin, blood tests, endoscopy or imaging, complications and response to established treatment. Seeing E. coli on a stool report does not diagnose AIEC and should not determine treatment.
For the wider evidence about FMT, see the separate FMT in Crohn's disease and ulcerative colitis guide.
Earlier research video
AI-assisted antibiotic research
This is the original visual and video from the existing page. It explains the enterololin discovery and why a narrow antibiotic may behave differently from a broad antibiotic.
My clinical view
AIEC is worth following because it may help us understand why Crohn's disease behaves differently from one person to another. At present, however, we cannot tell from a routine microbiome report whether AIEC is driving an individual's disease.
I would keep this in the research conversation while continuing to base care on established Crohn's disease assessment, monitoring and treatment.
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Frequently asked questions
Is AIEC the same as food-poisoning E. coli?
No. E. coli is a large family. AIEC is defined by how it behaves in laboratory testing and is being studied in relation to Crohn's disease.
Is AIEC the cause of Crohn's disease?
No single cause has been proven. AIEC may contribute to inflammation in some people, but it is not found in everyone.
Can a stool microbiome kit test for AIEC?
Routine commercial stool profiling does not reproduce the specialist bowel-lining and functional testing used to define AIEC in research.
Is enterololin available for Crohn's disease?
No. Enterololin is experimental and has been studied in laboratory work and mice. Human safety and effectiveness are not established.
Recommended related reading
If you would like to discuss Crohn's disease monitoring or treatment in your circumstances, you can use the appointment form below.
This page is for general education. It does not replace assessment by a gastroenterologist and is not advice to take antibiotics or seek FMT. Do not change Crohn's treatment without speaking to the clinical team.