XV. 5 Profile 5: Crohn's Disease
In Crohn's disease the response to FMT is weaker than in colitis, so it stays investigational and shows the most promise in the biologic-naive, ileocolonic subgroup.
| Parameter | Crohn's-specific detail |
|---|---|
| Evidence level | ★★☆☆☆ Limited. Small RCTs and open-label series; inconsistent results. Active research area; FMT considered investigational in Crohn's outside specialist centers. |
| Mechanism of dysbiosis | Transmural inflammation; reduced microbial diversity; Enterobacteriaceae expansion (adherent-invasive E. coli); mucus layer disruption; abnormal Paneth cell function reducing antimicrobial peptide secretion. |
| Primary microbiota targets | Reduce AIEC (adherent-invasive E. coli) load. Restore Bacteroidetes diversity. Support ileal mucosal healing through F. prausnitzii enrichment. |
| Protocol modification | Full 4-phase protocol. Prolonged compatibility assessment may be indicated to identify optimal donor for transmural inflammatory profile. Colonoscopic induction with ileal intubation preferred where structurally feasible. |
| Minimum transfer duration | 60 days minimum; extended to 90+ days in partial responders with active disease. Crohn's mucosal remodeling requires longer integration time than UC. |
| Priority exposome focus | Ultra-processed food elimination (mucosal emulsifiers directly disrupt barrier in Crohn's). Specific Carbohydrate Diet or low-FODMAP modification as adjunct. Smoking cessation critical (smoking worsens Crohn's through microbial and immune mechanisms). Stress management. |
| Expected response timeline | More variable than UC or rCDI. Partial symptomatic improvement possible 4–6 weeks. Sustained benefit requires full consolidation. Non-response at 12 weeks warrants protocol review. |
| Warning signs (Crohn's-specific) | Perianal pain or discharge during consolidation (fistula). Fever + right lower quadrant pain (abscess). Obstructive symptoms (stricture). Significant CRP or fecal calprotectin rise after initial improvement. |
Table 16 – Clinical profile: Crohn's Disease # Protocol parameters, evidence level, and clinical modifications specific to Crohn's disease.
The evidence in Crohn's disease is substantially weaker than in ulcerative colitis: a single randomised, sham-controlled pilot trial has been published [478], and the systematic reviews pool heterogeneous, largely cohort-based data, with almost no separate data on fistulizing or perianal forms [793]. On this basis routine use cannot be recommended.
Where Can FMT Have a Meaningful Role in Crohn's?
- Ileocolonic, biologic-naïve subgroup: the available data indicate that donor strain engraftment and the return of butyrate-producing taxa – among them Faecalibacterium prausnitzii – are associated with a more favourable response; a validated, phylogroup-level (Phylogroup II) donor-screening criterion is not yet available [478], [793].
- Steroid weaning alongside anti-TNF therapy: emerging evidence that FMT may help avoid flare during steroid taper.
- Clinical trial protocols: traditionally multi-donor + longer (12-week) consolidation. Single-donor approach is less successful in Crohn's.
Contraindications in Crohn's
| Situation | Rationale |
|---|---|
| Active fistulizing disease | Bacterial colonization of fistula tract during FMT is risky |
| Severe stricturing disease | Mechanical occlusion compromises engraftment efficacy |
| Recent resection (<6 months) | Bowel wall remodeling in progress – FMT timing can wait |
| Active perianal disease | Locally contaminated area, increased infectious risk |
Patients must be informed that Crohn-FMT remains at the experimental level, and in many countries is available only under institutional protocol.
References
[478] Sokol H, Landman C, Seksik P et al. Fecal microbiota transplantation to maintain remission in Crohn's disease: a pilot randomized controlled study. Microbiome. 2020. Link
Randomized, single-blind, sham-controlled pilot trial of FMT in adults with colonic or ileo-colonic Crohn's disease in steroid-induced clinical remission. Patients were randomized at remission to receive FMT or sham transplantation during colonoscopy; corticosteroids were tapered and follow-up colonoscopy performed at week 6. The trial provides the first randomized data on FMT for maintaining remission in CD, with modest signals supporting microbial engraftment as a candidate driver of clinical response and informing larger confirmatory studies.
[793] Fehily S, Basnayake C, Wright E, Kamm M. Fecal microbiota transplantation therapy in Crohn's disease: Systematic review. Journal of gastroenterology and hepatology. 2021. Link
FMT in Crohn's disease — systematic review — 15 studies (2 RCTs, 13 cohorts). Multiple FMT showed higher early response rate. Upper GI route early efficacy 75–100% vs. lower 30–58%. No serious adverse events occurred.