Efficacy and Safety of the Adjuvant Use of Probiotic Bacillus clausii Strains in Pediatric Irritable Bowel Syndrome: A Randomized, Double-Blind, Placebo-Controlled Study.

Paediatric drugs. 2023;25(1):115-126

Plain language summary

Irritable bowel syndrome (IBS) is considered both a health and a socioeconomic burden. Curative treatment for IBS is currently not available and current management strategies vary. Gut microbiota dysbiosis is increasingly considered as a vital factor in the etiopathogenetic of IBS; thus, gut microbiota are a potential therapeutic target. The aim of this study was to investigate the efficacy and safety of Bacillus clausii plus conventional treatment, compared with placebo plus conventional treatment, in children with IBS in Mexico. This study is a phase III, multicentre, randomised, placebo-controlled, double-blind, parallel clinical trial. Patients (n=259) were centrally randomised 1:1 to treatment with either B. clausii or placebo. Results show that IBS symptom relief in children was very high in both groups (B. clausii and placebo). In fact, there weren’t any significant differences between groups for proportion of patients with clinical improvements at Week 8 or any of the key secondary endpoints. Furthermore, the adverse event profile was similar between groups. Authors conclude that their study was not able to demonstrate the efficacy of B. clausii as an adjuvant to conventional treatment of patients with IBS.


OBJECTIVES Current irritable bowel syndrome (IBS) treatments have limited efficacy and probiotics like Bacillus clausii (B. clausii) were found to be effective in the management of several gastrointestinal disorders. This phase III trial assessed the efficacy and safety of adding B. clausii (four strains: O/C, N/R, SIN, T), versus placebo, to conventional treatment of pediatric IBS in Mexico. METHODS Patients aged 6-17 years 11 months with IBS (Rome IV) for at least 2 months were randomized to receive either B. clausii (oral suspension, total dose 4 billion spores/day) or placebo once daily for 8 weeks. All patients also received conventional treatment. The primary endpoint was the difference in the proportion of patients with clinical improvements at Week 8 (Global Assessment Questions [GAQ]). Secondary endpoints included responders by Subject's Global Assessment of Relief for Children with IBS (SGARC); number/consistency of stools; abdominal distention/bloating; abdominal pain/intensity; and IBS behavior. RESULTS 73.6% (95% confidence interval [CI] 67.3-80.0; B. clausii n = 129) and 78.5% (95% CI 72.5-84.4; placebo n = 130) of patients had symptom improvement (p = 0.8182). For Week 8 SGARC, 19.2% (B. clausii) and 20.9% (placebo) reported complete symptom relief. Stool evaluations, bloating, abdominal pain/intensity, and IBS behavior were similar between groups. Both treatments were well tolerated. CONCLUSION No significant differences in efficacy between B. clausii and placebo were demonstrated in addition to conventional treatment. The sample size calculation was based on an expected placebo/conventional treatment response of 30-40%. However, the actual treatment response observed was 80% and, thus, a study with larger population would be warranted. In addition, this study was conducted during the COVID-19 pandemic, when such controlled social conditions may have resulted in better diet, greater family stability, less psychological stress, and lower risk of infections exacerbating IBS, thereby improving symptoms in both groups. EUDRACT NUMBER 2018-004519-31.

Lifestyle medicine

Fundamental Clinical Imbalances : Digestive, absorptive and microbiological
Patient Centred Factors : Mediators/Irritable bowel syndrome
Environmental Inputs : Diet ; Nutrients ; Microorganisms
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Stool
Bioactive Substances : Probiotics ; Bacillus clausii

Methodological quality

Jadad score : 5
Allocation concealment : Yes