A Cochrane review «»1 «Allen SJ, Martinez EG, Gregorio GV, Dans LF. Probi...»1 included 63 studies with a total of 8014 subjects comparing a specified probiotic agent with a placebo or no probiotic in people with acute diarrhoea proven or presumed to be caused by an infectious agent. 56 trials recruited infants and children (age < 18 years, n = 6489).
The most common organisms evaluated were L. casei strain GG (13 trials), S. boulardii (10 trials) and Enterococcus lactic acid bacteria (LAB) SF68 (five trials). In forty-seven trials live organisms were tested, five tested a killed probiotic preparation. The average of the effect was significant for mean duration of diarrhoea (mean difference 24.76 hours; 95% CI 15.9 to 33.6 hours; 35 trials, n=4555) diarrhoea lasting ≥ 4 days (RR 0.41; 0.32 to 0.53; 29 trials, n=2853) and stool frequency on day 2 (mean difference 0.80; 0.45 to 1.14; 20 trials, n=2751).
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and outcomes).