[Up-to-date clinical and experimental basis for the use of probiotics]

OBJECTIVE: To evaluate the potential of probiotics or biotherapeutic agents for the prevention and/or treatment of selected intestinal infections. METHODS: Medline database was searched for all relevant articles between 1990 and February 1998. Bibliographies of articles were also used. All animal experiments and placebo-controlled human studies were reviewed in order to provide information on the mechanisms of action, potential efficacy, or adverse effects of these biotherapeutic agents. RESULTS: In the first part of this review, the different mechanisms of action that are effective in the treatment of diarrhea were discussed, and they were well demonstrated in laboratory animals. The most important are: enzymatic induction of disaccharidase activity, trophic effects on the intestinal mucosa, action in blocking bacterial toxins, and also induction of the immunologic response. Therapeutic effects of probiotics in humans, mainly in the gastrointestinal tract, were reported in the second part. Placebo-controlled studies have shown that biotherapeutic agents have been used successfully in the treatment of acute diarrhea in infants, traveler s diarrhea, antibiotic-associated diarrhea, with or without Clostridium difficile-associated enterocolitis (pseudomembranous colitis), and in immunosuppression-associated diarrhea, including AIDS. Lactobacillus, Bifidobacterium and Saccharomyces boulardii were the most important biotherapeutic agents to be considered. CONCLUSIONS: Currently, there is evidence that the administration of selected microorganisms is benefic in the prevention and treatment of certain intestinal infections. According to the literature, Saccharomyces boulardii is the most important probiotic. Possible future indications were discussed, such as the probable synergic effect of many probiotics due to their different and complementary mechanisms of action. The importance of new experimental and clinical studies for the better understanding of actions and the use of probiotics in other clinical situations was emphasized.