Antibiotic-associated diarrhea is a common complication of antibiotic treatment. A placebo-controlled, randomized clinical trial was designed to evaluate the efficacy of a multispecies probiotic in the prevention of antibiotic-associated diarrhea in pediatric inpatients and outpatients.

Eligibility criteria included being three months to 18 years of age and recruited within 24 hours of the initiation of broad-spectrum oral or IV antibiotic therapy. The 350 participants (mean age, 50 months) enrolled in the study were randomized to either a probiotic containing eight bacterial strains or a placebo for the duration of antibiotic therapy and for seven days afterward. The primary outcome was antibiotic-associated diarrhea, defined as three or more loose or watery stools per day in a 24-hour period, caused either by Clostridioides difficile or unexplained etiology, after testing for common diarrheal pathogens.

Compared with placebo, the probiotic didn't have a significant effect on the risk of antibiotic-associated diarrhea. Patients who received the probiotic did, however, have a significantly lower risk of diarrhea regardless of etiology. They were also less likely to need IV rehydration due to diarrhea. There were no significant differences between the groups in other outcomes.

Among the limitations of the study were that loss to follow-up was relatively high, the duration of follow-up was limited, and there was a potential misclassification between the antibiotic-associated diarrhea and diarrhea outcomes due to the limited diagnostic accuracy of immunoassays.

The authors point out that the cause of diarrhea may not be relevant so long as the preventive intervention is effective, concluding that the studied probiotic may be an option for the prevention of diarrhea in children receiving antibiotic treatment.