Lack of effect of Lactobacillus GG on antibiotic-associated diarrhea: A randomized, placebo-controlled trial

Objective: To assess the efficacy of Lactobacillus GG in preventing antibiotic-associated diarrhea (AAD) in adults and, secondarily, to assess the effect of coadministered Lactobacillus GG on the number of tests performed to determine the cause of diarrhea. Patients and Methods: In this prospective, randomized, double-blind, placebo-controlled trial conducted from July 1998 to October 1999, 302 hospitalized patients receiving antibiotics were randomized to receive Lactobacillus GG, 20 × 10⁹ CFU/d, or placebo for 14 days. Subjects recorded the number of stools and their consistency daily for 21 days. The primary outcome was the proportion of patients who developed diarrhea in the first 21 days after enrollment. Weekly telephone follow-up was also performed. Results were analyzed in an intention-to-treat fashion. Results: Diarrhea developed in 39 (29.3%) of 133 patients randomized to receive Lactobacillus GG and in 40 (29.9%) of 134 patients randomized to receive placebo (P=.93). No additional difference in the rate of occurrence of diarrhea was found between treatment and placebo patients in a subgroup analysis of those treated with β-lactam vs non-β-lactam antibiotics. Too few patients had stool cultures, additional laboratory tests for diarrhea, or a positive diagnosis of Clostridium difficile infection to assess between-group differences. Conclusion: Lactobacillus GG in a dose of 20 × 10⁹ CFU/d did not reduce the rate of occurrence of diarrhea in this sample of 267 adult patients taking antibiotics initially administered in the hospital setting.