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Study on the Effectiveness of E. coli DSM 17252 for Patients with Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D)

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a condition known as Irritable Bowel Syndrome, specifically the type that mainly causes diarrhea, referred to as IBS-D. The treatment being tested is called Symbioflor®2, which contains living bacteria known as Escherichia coli DSM 17252. The trial will compare the effects of this treatment to a placebo, which looks and feels the same as the treatment but does not contain the active bacteria.

The purpose of the study is to see how effective Symbioflor®2 is in reducing the frequency and severity of symptoms in patients with IBS-D. It will also assess the safety and how well patients tolerate the treatment. Participants in the study will take the treatment or placebo orally, meaning they will swallow it, over a period of 26 weeks. During this time, researchers will monitor changes in symptoms and any side effects experienced by the participants.

Throughout the study, participants will be asked to report on their symptoms, such as abdominal pain and stool consistency, using simple scales. This will help researchers determine if the treatment is making a significant difference compared to the placebo. The study aims to provide valuable information on whether Symbioflor®2 can be a helpful treatment option for those suffering from IBS-D.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, the patient will be informed about the trial's objective, which is to evaluate the effectiveness, safety, and tolerability of the oral treatment with living bacteria of E. coli DSM 17252 (Symbioflor®2) in patients with diarrhoea-predominant irritable bowel syndrome (IBS-D).

    The patient will be required to provide written informed consent before participating in the trial.

  2. Step 2

    Initial assessment

    The patient will undergo an initial assessment to confirm eligibility, which includes a diagnosis of irritable bowel syndrome according to specific criteria and a colonoscopy with no clinically relevant findings.

    Female patients of childbearing potential must have a negative pregnancy test at screening and baseline.

  3. Step 3

    Treatment phase

    The patient will receive either the Symbioflor®2 oral drops or a placebo. The placebo is identical in appearance and composition to Symbioflor®2, except it does not contain the active ingredient.

    The treatment will be administered orally as drops, and the patient will be instructed on the dosage and frequency of administration.

  4. Step 4

    Monitoring and evaluation

    Throughout the trial, the patient will be monitored for changes in symptoms using the Bristol Stool Scale and an 11-point numeric rating scale for abdominal pain intensity.

    The primary goal is to achieve at least a 50% reduction in the number of days with stool consistency of 6 or 7 and a decrease in the weekly average of worst abdominal pain.

  5. Step 5

    Completion of the trial

    The trial is expected to last for 26 weeks, during which the patient will continue to receive the treatment and undergo regular assessments.

    Upon completion, the patient's response to the treatment will be evaluated based on the improvement in IBS symptoms and overall tolerability of the treatment.

Who can join the trial?

17 criteria

  • Must be a male or female outpatient aged 18 years or older.
  • Must have a diagnosis of irritable bowel syndrome (IBS) according to Rome IV criteria, which includes:
    • Recurrent abdominal pain, on average, at least 1 day per week in the last 3 months.
    • Pain associated with two or more of the following:
      • Related to defecation (going to the bathroom).
      • Associated with a change in how often you have a bowel movement.
      • Associated with a change in the form (appearance) of your stool.
      • Symptoms must have been present for the last 3 months.
      • IBS symptoms must have started at least 6 months ago.
      • Must have the IBS-D subtype, where abnormal stools are usually diarrhea.
      • Must have had a colonoscopy (a test to look inside the colon) with no important findings:
        • For patients younger than 50 years, the colonoscopy must have been done.
        • For patients 50 years or older, the colonoscopy must have been done within the last 5 years.
        • Female patients who can have children must be surgically sterilized or use a highly effective method of birth control, with a negative pregnancy test at the start of the study.
        • Must be willing to avoid significant changes in diet, fiber intake, fluid intake, or physical activity during the study.
        • Must be willing to avoid using other medications for IBS treatment, including probiotic medication.
        • Must be able to follow the treatment plan.
        • Must have enough knowledge of the German language to understand trial instructions and rating scales.
        • Must provide written informed consent before joining the study.
        • Must have an email account and internet access available.

Who cannot join the trial?

3 criteria

  • Patients who are not diagnosed with Irritable Bowel Syndrome (IBS) cannot participate. IBS is a condition that affects the digestive system, causing symptoms like stomach pain and changes in bowel habits.
  • Patients who are not within the specified age range for the study cannot participate. The study includes certain age groups, so if you are outside these groups, you may not be eligible.
  • Patients who are part of a vulnerable population cannot participate. This means people who might need special protection or care, such as those with certain disabilities or conditions, are not included.
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Investigated drugs

Symbioflor®2 is a treatment that contains living bacteria of E. coli DSM 17252. It is used in this trial to help patients with diarrhoea-predominant irritable bowel syndrome (IBS-D). The goal is to see if it can reduce the frequency and severity of IBS-D symptoms. The trial also aims to check how safe and tolerable this treatment is for patients.

What is already known about the treatment

Symbioflor®2 – This medication is administered orally in the form of living bacteria, specifically E. coli DSM 17252. It is currently being studied in clinical trials to assess its effectiveness, safety, and tolerability for treating diarrhea-predominant irritable bowel syndrome (IBS-D). The main therapeutic indication is to alleviate the symptoms of IBS-D, such as frequent and severe diarrhea. At the molecular level, it is believed to work by modulating the gut microbiota, which may help restore balance in the intestinal environment. Symbioflor®2 is classified as a probiotic, which is a type of supplement containing beneficial bacteria.

Investigated diseases

Irritable Bowel Syndrome – This is a common disorder affecting the large intestine, characterized by symptoms such as cramping, abdominal pain, bloating, gas, and diarrhea or constipation, or both. The exact cause of irritable bowel syndrome is unknown, but it is believed to involve a combination of abnormal gastrointestinal tract movements, increased sensitivity to pain, and changes in the gut microbiota. Symptoms can vary in intensity and may be triggered by certain foods, stress, or hormonal changes. The condition is chronic, meaning it requires long-term management, and symptoms can fluctuate over time. It does not cause changes in bowel tissue or increase the risk of colorectal cancer.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-512104-19-00Protocol codeSymSF2Estimated enrolment422 patientsSponsorSymbioPharm GmbH

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