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

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

Status

Not yet recruiting

Phases

Phase 4

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT07426705

Acronym

SIBO-Probiotic

Enrollment

100

Registered

2026-02-23

Start date

2026-02-15

Completion date

2027-07-15

Last updated

2026-02-23

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Small Intestinal Bacterial Overgrowth Syndrome (SIBO), IBS

Keywords

SIBO, IBS, probiotic

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.

Interventions

DIETARY_SUPPLEMENTProbiotic preparation

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.

OTHERPlacebo

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.

DRUGRifaximin (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.

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Masking

QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Intervention model description

Randomized, double-blind, placebo-controlled, parallel-group design.

Eligibility

Sex/Gender

ALL

Age

18 Years to 75 Years

Healthy volunteers

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.

Design outcomes

Primary

Measure	Time frame	Description
SIBO eradication rate	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

Measure	Time frame	Description
SIBO recurrence rate after completion of probiotic therapy	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.

Contacts

CONTACTPaulina PANUFNIK

paulina.panufnik@pimmswia.gov.pl477221420

CONTACTAleksandra Perdek

477221242

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 24, 2026