Probiotic Bacteria May Prevent Antibiotic Diarrhea

Researchers at RAND Health (Santa Monica, CA, USA), Cedars-Sinai Medical Center (Los Angeles, CA, USA; cedars-sinai.edu), and other institutions conducted a meta-analysis that included 82 randomized controlled trials, 57 of which used Lactobacillus-based interventions alone or in combination with other genera of probiotics (32 of them with Bifidobacterium). All but two trials used probiotics to prevent rather than treat existing AAD. The effect on diarrhea risk could be pooled from 63 of the trials, with a total of 11,811 participants, and remained significant when excluding any individual trial.

The results indicated a statistically significant association of probiotic administration with reduction in AAD. This result was relatively insensitive to numerous subgroup analyses, including adults versus children, outpatient versus inpatient care, or by duration of antibiotic treatment. However, the researchers stressed, there exists significant heterogeneity in the pooled results, and the evidence is insufficient to determine whether this association varies systematically by population, antibiotic characteristic, or probiotic preparation. The study was published in the May 9, 2012, issue of the Journal of the American Medical Association (JAMA).

“Potentially, probiotics maintain or restore gut microecology during or after antibiotic treatment through receptor competition, competition for nutrients, inhibition of epithelial and mucosal adherence of pathogens, introduction of lower colonic pH favoring the growth of nonpathogenic species, stimulation of immunity, or production of antimicrobial substances,” concluded lead author Susanne Hempel, PhD, of RAND Health, and colleagues. “Determining which populations would benefit most from adjunct probiotics therapy is an ongoing challenge; it must be considered that antibiotic-associated diarrhea does not occur in the majority of patients and when it occurs, it is usually self-limiting.”

Probiotic organisms are live microorganisms thought to be beneficial to the host organism. Lactic acid bacteria (LAB, Lactobacillus) and bifidobacteria are the most common types of microbes used as probiotics; but certain yeasts and bacilli may also be used. Probiotics are commonly consumed as part of fermented foods with specially added active live cultures, such as in yogurt, or in dietary supplements.

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