Invasive infections due to Saccharomyces boulardii (Ultra-levure).

(1) Saccharomyces boulardii, a yeast closely related to Saccharomyces cerevisiae, is marketed in France for adjuvant treatment of diarrhoea, although it has no proven efficacy. (2) Invasive infections due to Saccharomyces boulardii have occurred. Most of the patients had gastrointestinal disorders, an intravenous catheter, or ongoing antibiotic treatment. Only 25% of patients were immunosuppressed. (3) Unless the value of this type of treatment based on live microorganisms is demonstrated in methodologically sound clinical trials, it is best to avoid prescribing it to fragile patients.