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

NCT07426705 | Not Yet Recruiting Phase 4

• 1 other identifier: 34/BK/2025
• Study Type: interventional
• Target: 100
• Locations: 0 countries
• Sites: N/A

Brief Summary

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.

Conditions

Small Intestinal Bacterial Overgrowth Syndrome (SIBO); IBS

Keywords

SIBO; IBS; probiotic

Outcome Measures

Primary Outcomes (1)

• SIBO eradication rate

  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).

  4 weeks

Secondary Outcomes (1)

• SIBO recurrence rate after completion of probiotic therapy

  10 weeks

Study Arms (2)

Probiotic Group

EXPERIMENTAL

Participants will receive rifaximin followed by the probiotic preparation according to the study protocol.

Dietary Supplement: Probiotic preparation; Drug: Rifaximin (drug)

Placebo Group

PLACEBO COMPARATOR

Participants will receive rifaximin followed by placebo according to the study protocol.

Other: Placebo; Drug: Rifaximin (drug)

Interventions

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.

Probiotic Group

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.

Placebo Group

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.

Placebo Group; Probiotic Group

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

• 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.

Sponsors & Collaborators

• Państwowy Instytut Medyczny Ministerstwa Spraw Wewnętrznych i Administracji: lead
• URGO Poland: collaborator

MeSH Terms

Interventions

Rifaximin; Pharmaceutical Preparations

Intervention Hierarchy (Ancestors)

Rifamycins; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds; Lactams, Macrocyclic; Macrocyclic Compounds; Polycyclic Compounds

Central Study Contacts

Paulina PANUFNIK

CONTACT

477221420; paulina.panufnik@pimmswia.gov.pl

Aleksandra Perdek

CONTACT

477221242

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR

Model Details: Randomized, double-blind, placebo-controlled, parallel-group design.

Study Record Dates

• First Submitted: February 16, 2026
• First Posted: February 23, 2026
• Study Start: February 15, 2026
• Primary Completion (Estimated): July 15, 2027
• Study Completion (Estimated): July 15, 2027
• Last Updated: February 23, 2026

Record last verified: 2026-02