Scientists Engineer Safer Probiotic for Immunocompromised Patients

An international team of researchers has modified the probiotic yeast Saccharomyces boulardii to make it safer for people with weakened immune systems, including infants and older adults. The study found that the modified yeast was less likely to cause infections while still maintaining its probiotic benefits. The findings were reported in the journal Communications Biology.

Saccharomyces boulardii is commonly used as a probiotic to promote gut health, but in rare cases, it has caused bloodstream infections in vulnerable patients. “While these cases are rarely reported, they can be serious—even fatal,” said Alexandra Imre, a postdoctoral researcher at North Carolina (NC) State University and first author of the study. The researchers examined yeast strains and identified two genes linked to the yeast's ability to tolerate osmotic stress, a trait associated with higher virulence.

Experiments showed that deleting the ENA1 gene significantly reduced the yeast's ability to cause infection. In mouse tests, survival rates increased from 30-40% to 100% after the gene was removed. The study revealed that the edited yeast still showed probiotic activity, including the ability to suppress harmful bacteria. The results highlight the potential of modified probiotics that could safely benefit immunocompromised patients.

For more information, read the news release from NC State University.