Against this background, two placebo-controlled, randomized, double-blind studies have evaluated the effects of the probiotic Bacillus clausii strains O/C, N/R, SIN and T against digestive side effects of Helicobacter pylori eradication treatment. The first of the two studies randomized 120 patients undergoing triple therapy with rabeprazole 20 mg twice daily, clarithromycin 500 mg twice daily and amoxicillin 1 g twice daily for 7 days to either receive placebo or B. clausii suspension thrice daily (total daily dose of 6 billion colony-forming units [CFU]) for 14 days starting on the first day of treatment . Gastrointestinal side effects were recorded for 4 weeks from the start of therapy based on a validated questionnaire. A second study of similar design randomized 130 patients using similar inclusion criteria to receive placebo or B. clausii as capsule . The main protocol difference was that the sample size in the second study was based on a power calculation and that it had a defined primary endpoint, i.e., occurrence of diarrhea in the first week.
B. clausii reduced the incidence of diarrhea to a clinically meaningful and statistically significant extent in the first week of treatment irrespective of differences in the incidence of diarrhea between the two studies (Fig. 1). Despite a lower incidence of diarrhea in the second week, the risk reduction by B. clausii was similar. Moreover, when diarrhea occurred in the B. clausii group, it was of shorter duration than in the placebo group. Regarding other outcome parameters, the Nista study found a reduction of epigastric pain in both weeks, whereas the Plomer trial made this observation only in the second week. Of note, H. pylori eradication rates were similar in the presence of placebo or B. clausii. We conclude that treatment with B. clausii compared to placebo reduces the incidence of the most common gastrointestinal side-effects related to H. pylori eradication triple treatment in symptom-free, H. pylori-positive subjects.
Fig. 1. Incidence of diarrhea in patients undergoing triple therapy for Helicobacter pylori eradication in the studies by Nista et al.  and Plomer et al. . Corresponding relative risk was 0.301 [95% confidence interval 0.12; 0.76] and 0.61 [0.39; 0.97].
Conflict of interest: M. Plomer and M. III Perez are employees of Sanofi-Aventis.
Disclosure: Medical writing and publication funded by Sanofi-Aventis Deutschland GmbH.