Food and probiotic strains from the Saccharomyces cerevisiae species as a possible origin of human systemic infections.

We report four cases of blood cultures testing positive for yeast strains belonging to the species Saccharomyces cerevisiae. Using molecular techniques, RFLP of mtDNA and delta-PCR amplification, we show the association of two of the isolates with non-clinical strains. Specifically, with two commercial bread-making strains and the therapeutic S. boulardii strain. The association of S. boulardii with cases of fungemia has been reported previously. Nevertheless, this is the first time that a baker's yeast has been isolated from blood.