Gut microbiome in post-infectious irritable bowel syndrome

Informed Ecological Rewiring of Gut Microbiome for Dysbiosis-associated Disorders

This project will test whether adults with post‑infectious IBS have different gut microbiome patterns compared with people who recovered from an infection and healthy adults.

Quick facts

• Study type: Observational
• Enrollment: 315 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Fondazione Policlinico Universitario Agostino Gemelli IRCCS (Academic / other)
• Locations: 1 site (Rome)
• Trial ID: NCT07517029 on ClinicalTrials.gov

What this trial studies

This is a prospective, multicenter observational study that will use whole‑genome shotgun sequencing to profile the gut microbiome in 315 adults divided equally into three groups: PI‑IBS patients, post‑infectious individuals without IBS, and healthy controls. PI‑IBS patients will complete baseline clinical assessments including IBS‑SSS and provide stool samples at baseline and monthly for three months, while control participants provide a single baseline sample. All samples will be processed under standardized conditions and analyzed centrally to identify reproducible microbial signatures and taxa linked to disease presence and symptom severity. The study represents the first aim of a broader program to inform precision microbiome modulation strategies for PI‑IBS.

Who should consider this trial

Good fit: Adults (≥18) diagnosed with post‑infectious IBS by Rome IV criteria, diagnosed within the prior three months, who can provide stool samples and attend monthly follow‑up visits are ideal candidates.

Not a fit: People with chronic organic GI diseases (like IBD), metabolic syndrome, obesity, diabetes, GI cancers, systemic autoimmune disorders, or a history of major abdominal surgery are excluded and unlikely to benefit from this study.

Why it matters

Potential benefit: If successful, this work could identify microbial signatures that lead to new diagnostic markers or microbiome‑targeted therapies for people with PI‑IBS.

How similar studies have performed: Prior microbiome studies in IBS have reported altered bacterial patterns but results have been inconsistent, so this high‑resolution WGS approach aims to find more reproducible signatures.

Eligibility criteria

PI-IBS patients (n = 105)

* Inclusion criteria

  * Age ≥ 18 years old
  * PI-IBS diagnosed according to Rome IV criteria (33).
  * Diagnosis no earlier than 3 months before enrollment.
  * Written informed consent and compliance with study procedures.
* Exclusion criteria

  * Chronic organic gastrointestinal (GI) disorders (e.g. Inflammatory Bowel Disease -IBD), metabolic syndrome, obesity, diabetes, GI cancers, systemic autoimmune disorders.
  * History of major abdominal surgery.

Control cohort #1 - Post-infectious non-IBS (n = 105)

* Inclusion criteria

  * Age ≥ 18 years old
  * History of acute infectious gastroenteritis \>6 months before enrollment.
  * Complete recovery without persistent GI symptoms.
* Exclusion criteria

  * Current or past diagnosis of IBS.
  * Any chronic GI or systemic disorders.

Control cohort #2 - Healthy subjects (n = 105)

* Inclusion criteria

  * Age ≥ 18 years old
  * Healthy donors from FMT program or blood donor program.
  * No history of GI or systemic disorders.
* Exclusion criteria

  * Any GI or systemic chronic condition.
  * Recent antibiotics/probiotics (\<4 weeks).
  * Chronic medication affecting microbiome composition (e.g. PPI)

Where this trial is running

Rome

• Digestive Disease Center, Fondazione Policlinico Univesitario A. Gemelli IRCCS — Rome, Italy (Recruiting)

Study contacts

• Principal investigator: Gianluca Ianiro — Fondazione Policlinico Universitario Agostino Gemelli IRCCS
• Study coordinator: Gianluca Ianiro

Conditions IBS - Irritable Bowel Syndrome; Post Infection Syndrome