Probiotics to Prevent Antibiotic-Associated Diarrhea: A Randomized Trial

Summary and Comment |
September 3, 2013

Probiotics to Prevent Antibiotic-Associated Diarrhea: A Randomized Trial

  1. Bruce Soloway, MD

A multistrain preparation conferred no benefit in older patients.

  1. Bruce Soloway, MD

In a 2012 meta-analysis, probiotic use was associated with 42% lower risk for antibiotic-associated diarrhea (AAD; JAMA 2012; 307:1959). However, the 63 trials varied widely in settings, participants, and regimens, and many were small or poorly documented, which yielded unclear clinical implications. To address some of these flaws, researchers in the U.K. identified 2941 older patients (age, >65) who were about to start or recently were exposed to systemic antibiotics in five hospitals; patients were randomized to receive single capsules that contained either a multistrain preparation of Lactobacilli and Bifidobacteria or placebo once daily for 21 days. AAD was defined as diarrhea without an identified pathogen and without an alternative explanation.

During an 8-week follow-up, incidence of AAD (including Clostridium difficile–associated diarrhea) was similar in the probiotic and placebo groups (10.8% and 10.4%) as was incidence of C. difficile–associated diarrhea specifically (0.8% and 1.2%). Rates of adverse events also were similar in the two groups.


The authors of the 2012 meta-analysis called for large, randomized clinical trials to address the limitations of the analysis; now, the first such trial has come to a contradictory conclusion. The pathophysiology of antibiotic-associated diarrhea is understood poorly, which complicates efforts to identify specific microbes and microbial strains that might lower risk for AAD in defined populations. For now, other methods, from handwashing to antimicrobial stewardship, might be more effective in preventing AAD, including C. difficile–associated diarrhea.

Editor Disclosures at Time of Publication

  • Disclosures for Bruce Soloway, MD at time of publication Nothing to disclose


Reader Comments (3)

PETER UNDERWOOD Other Healthcare Professional, Pharmacology/Pharmacy, Hospital

Per the methods of the study, the microbial preparation used contained 60 billion live bacteria (noted as "high dose, multi-strain perparation" in the introduction). The investigators even tested their product mid-study and found the capsules still contained a large quantity of viable bacteria (see results section after compliance). Many OTC "probiotic" products contain hundreds of million of live bacteria per capsule or possibly up to 1 billion bacteria, but I haven't seen any that have 10's of billions of live bacteria such as the product described in this study (source was not identified). This was not a homeopathic dose of microbial poduct but a high dose and the study notes this.

Filip Babnic MD Physician, Internal Medicine, hospital setting

I have to strongly agree with David, why are we testing "homeopathic" dose of probiotic against placebo ?

David L. Keller, M.D. Physician, Internal Medicine, clinic

I would have given the probiotic three times a day instead of once. Also, how did the investigators make certain that the probiotics were live, active cultures? Capsules of dessicated "pro-biotic" powders sitting on a shelf in a bottle cannot be expected to replenish the colon with beneficial living flora. The probiotics should be freshly cultured and verified living.

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