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NCT Number: NCT07426705

Effect of Multispecies Probiotic Supplementation on the Efficacy of Rifaximin α Therapy in Patients With Small Intestinal Bacterial Overgrowth (SIBO): a Randomized Placebo-controlled Trial

Small intestinal bacterial overgrowth (SIBO) is a common condition associated with gastrointestinal symptoms such as bloating, abdominal pain, diarrhea, and constipation, particularly in patients with irritable bowel syndrome. Antibiotic therapy with rifaximin is commonly used, but relapse rates remain high.

This randomized, placebo-controlled clinical trial aims to evaluate whether supplementation with a multispecies probiotic containing Enterococcus faecium and Bacillus subtilis improves the effectiveness of rifaximin therapy in adult patients with SIBO.

Participants will be randomly assigned to receive either rifaximin plus the probiotic or rifaximin plus placebo. Clinical assessments will include hydrogen breath testing and evaluation of gastrointestinal symptoms using standardized questionnaires at baseline and during follow-up visits.

The study is being conducted at a single academic medical center in Poland and is sponsored by Państwowy Instytut Medyczny MSWiA. The probiotic and rifaximin are provided by Urgo.

The results of this study may help determine whether probiotic supplementation can improve treatment outcomes and reduce recurrence of SIBO.

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Key information

Conditions

Small Intestinal Bacterial Overgrowth Syndrome (SIBO) IBS

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥18 years.
  • Meets Rome IV criteria for irritable bowel syndrome.
  • Written informed consent to participate in the study.

Exclusion criteria

  • Lack of cooperation with investigators.
  • Age >75 years.
  • Need for modification of gastrointestinal treatment during the study.
  • Use of antibiotics within 4 weeks before screening.
  • Use of probiotics within 7 days before screening.
  • Endoscopic examination within 6 weeks before screening or during the study without investigator approval.
  • History of abdominal surgery.
  • Crohn's disease, ulcerative colitis, microscopic colitis, celiac disease, cystic fibrosis, chronic pancreatitis, liver cirrhosis, or end-stage renal disease.
  • Low FODMAP diet within 4 weeks before screening.
  • Pregnancy or breastfeeding.
  • Lactulose intolerance.

Treatment and study plan

Probiotic preparation

Dietary Supplement

Oral probiotic preparation administered once daily for 6 weeks following completion of antibiotic treatment for small intestinal bacterial overgrowth (SIBO). The product contains a defined combination of bacterial strains and is intended to support restoration of gut microbiota and reduce recurrence of SIBO.

Placebo

Other

Matching oral placebo capsule administered once daily for 6 weeks following completion of antibiotic treatment for small intestinal bacterial overgrowth (SIBO). The placebo is identical in appearance, taste, and packaging to the probiotic product but contains no live microorganisms.

Rifaximin (drug)

Drug

Rifaximin is administered to all participants as background standard therapy for SIBO at a dose of 1600 mg per day orally for 14 days. The randomized comparison concerns adjunctive probiotic versus placebo.

Primary outcomes

  1. SIBO eradication rate

    Time frame: 4 weeks

    Proportion of participants with eradicated small intestinal bacterial overgrowth (SIBO), defined as a negative hydrogen breath test, assessed 4 weeks after treatment initiation (rifaximin for 14 days plus probiotic for 4 weeks).

Secondary outcomes

  1. SIBO recurrence rate after completion of probiotic therapy

    Time frame: 10 weeks

    Proportion of participants with recurrent SIBO, defined as a positive hydrogen breath test, assessed 4 weeks after completion of 6 weeks of probiotic supplementation following rifaximin treatment.

Study contacts

Contact information is provided by the study sponsor or research team.

Aleksandra Perdek

CONTACT

477221242

Paulina PANUFNIK

CONTACT

[email protected]

477221420

Sponsors and collaborators

Lead sponsor

Państwowy Instytut Medyczny Ministerstwa Spraw Wewnętrznych i Administracji

Other Gov

Collaborators

  • URGO Poland

Registry information

Official study title

Effect of Enterococcus Faecium and Bacillus Subtilis-Containing Multispecies Probiotic Supplementation on the Therapeutic Efficacy of Rifaximin α in Patients With Small Intestinal Bacterial Overgrowth (SIBO): a Prospective, Randomized, Placebo-controlled Trial

Acronym: SIBO-Probiotic

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Feb 23, 2026
Registry last updated
Feb 23, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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