By Joseph E. Scherger, MD, MPH

Core Faculty, Eisenhower Health Family Medicine, Residency Program, Eisenhower Health Center, La Quinta, CA; Clinical Professor, Keck School of Medicine, University of Southern California, Los Angeles

SYNOPSIS: Saccharomyces boulardii is a probiotic yeast that may cause fungemia and other fungal infections.

SOURCE: Rannikko J, Holmberg V, Karppelin M, et al. Fungemia and other fungal infections associated with use of Saccharomyces boulardii probiotic supplements. Emerg Infect Dis 2021;27. doi: 10.3201/eid2708.210018.

Rannikko et al reviewed the medical records of patients with positive blood cultures for Saccharomyces boulardii at five university hospitals in Finland between 2009 and 2018. The authors identified 46 patients, at least 20 of whom were using a Saccharomyces boulardii probiotic. Compared with a control group, the odds ratio for using the probiotic was 14. A total of 37% of these patients died. In addition, the authors found 1,153 nonblood isolates of Saccharomyces species; most commonly, these were associated with gastrointestinal disease.


Probiotics are live organisms given to patients for health benefits, often to improve the gut microbiome. Usually, probiotics are a combination of several bacterial species, and most are safe. Saccharomyces boulardii is a yeast probiotic widely used to treat certain types of diarrhea, such as rotavirus infection in children and for ulcer prevention.1,2 This report from Finland should remind clinicians that giving live organisms can be dangerous, especially to immune-compromised patients.


  1. WebMD. Saccharomyces boulardii.
  2. Kelesidis T, Pothoulakis C. Efficacy and safety of the probiotic Saccharomyces boulardii for the prevention and therapy of gastrointestinal disorders. Therap Adv Gastroenterol 2012;5:111-125.