Incidence of Saccharomyces cerevisiae fungemia in hospitalised patients administered Saccharomyces boulardii probiotic.

Background: Bloodstream infection is an untoward effect of probiotic administration described by case reports and a cited reason to avoid using in the critically ill. The incidence rate of bloodstream infection in a population administered probiotics remains unknown.
Methods: A retrospective observational analysis of incident Saccharomyces cerevisiae fungemia in a population of hospitalised patients administered Saccharomyces boulardii for primary prevention of hospital-onset Clostridioides difficile infection. Adult patients admitted to an inpatient medical unit for 48-h or more between January 1, 2016 and December 31, 2019 are included. Facility medication administration records and microbiology records were evaluated for S boulardii probiotic administration and incidence of S cerevisiae positive blood cultures. Microbiologic identification methods were unable to distinguish S cerevisiae from S boulardii.
Results: Administration of S boulardii probiotic occurred in 16,404 of 46,729 patients analysed. S cerevisiae fungemia was identified in 18 probiotic recipients (0.11%). The observed incidence of fungemia attributable to S boulardii administration is 1.70 cases per 10,000 patient-days. Central-line days numbered 52,949 yielding an incidence of 0.26 cases of S cerevisiae per 1,000 central-line days. Intensive care unit admission was significantly associated with an increase in the risk of S cerevisiae (OR 6.55, CI 2.28-18.87), incidence rate of 0.47 cases per 1,000 patient-days.
Conclusion: The risk of bloodstream infection as a result of S boulardii probiotic use appears restricted to S boulardii recipients. The risk for probiotic-related bloodstream infection does not appear greater than the risk of any hospital-acquired bloodstream infection both inside and outside of the intensive care unit.
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