Safety of dietary supplements is conducted postmarketing. Therefore, much of the safety data on use of S. boulardii
as a probiotic “drug” are derived from case reports. Saccharomyces
fungemia is the most severe complication secondary to administration of the probiotic. S. cerevisiae
and S. boulardii
have been referred to in the literature interchangeably and have recently been shown by genetic fingerprinting and gene sequencing to be similar on a genetic level and to possibly share metabolic properties (26
The most comprehensive literature review on incidence of invasive Saccharomyces
infections was conducted by Enache-Angoulvant et al. (27
). They identified 91 documented cases of invasive Saccharomyces
infection in the literature (54 cases of S. cerevisiae
invasive infections vs. 37 cases of S. boulardii
fungemia). In particular, patients infected with S. boulardii
were more likely than patients infected with S. cerevisiae
to have digestive tract disease (58% vs. 6%; p<0.01), to have intravenous catheters (83% vs. 29%; p<0.0001), and to be hospitalized in an intensive care unit (32% vs. 0.05%, p<0.01). The use of biotherapeutic agents containing S. boulardii
was associated with 40% of all invasive cases. A previously conducted literature review by Muñoz et al. identified 60 cases of fungemia caused by S. cerevisiae
). Of note, 48% of patients with fungemia had received a S. boulardii
probiotic preparation, and another 8% were near patients who had received these agents. The latter finding suggests that S. boulardii
administration presents an environmental risk for patients who are not receiving the agents.
When Hennequin et al. investigated air and surface contamination related to the opening of a 500-mg packet of freeze-dried S. boulardii,
they found that the simple act of opening a packet of S. boulardii
produced substantial air contamination (29
). Organisms persisted on the arm of the simulated patient 30 minutes after the product was opened and as long as 2 hours on the surrounding table surface. The hands of the technician who had opened the packet were noted to be highly and persistently contaminated despite vigorous handwashing.
Several factors constitute excessive and undue risk for development of Saccharomyces fungemia during probiotic administration. These factors are the patient’s immunocompromised state during critical illness, the potential for live yeast spore contamination of healthcare workers’ hands during preparation of the probiotic capsule for administration, and introduction of live yeast from contaminated hands to catheter sites (and patient’s bloodstream).