Background: Probiotics may be of help for the management of acute diarrhoea, however, the effect is strain specific and efficacy needs to be proven.

Aim: To test the efficacy and safety of Lactobacillus reuteri DSM 17938 derived from L. reuteri ATCC 55730 in children with acute diarrhoea. Primary outcomes were the rate of unresolved diarrhoea after 3 days of treatment and duration of diarrhoea.

Methods: Children (6-36 months), hospitalised in three paediatric hospitals in Southern Italy for acute diarrhoea with clinical signs of dehydration were randomised to receive in a double-blind fashion either L. reuteri (dose of 4 × 10(8) colony-forming units/die) or placebo.

Results: Out of 96 eligible children, 74 were enrolled, five patients were withdrawn; 35 in the L. reuteri group and 34 in the placebo group. Lactobacillus reuteri significantly reduced the duration of watery diarrhoea as compared with placebo (2.1 ± 1.7 days vs. 3.3 ± 2.1 days; P < 0.03); on day two and three of treatment watery diarrhoea persisted in 82% and 74% of the placebo and 55% and 45% of the L. reuteri recipients respectively (P < 0.01; P < 0.03). Finally, children receiving L. reuteri had a significantly lower relapse rate of diarrhoea (15% vs. 42%; P < 0.03). There was not a significant difference in hospital stay between the groups. No adverse events were recorded.

Conclusion: Our study shows that L. reuteri DSM 17938 as an adjunct to rehydration therapy is efficacious in the treatment of acute diarrhoea reducing the frequency, duration and recrudescence rate of the disease.