Destructive Duo

The yeast Candida albicans (turquoise) and the bacterium Enterococcus faecalis (purple) are two microorganisms that generally live harmoniously inside the human body. Sometimes, E. faecalis has a suppressive effect on the yeast, but other times, these two bugs form a dastardly alliance that results in destructive infections. Scientists are therefore trying to understand how the same pair of organisms can have such different relationships. New research indicates that the particular strain of E. faecalis determines the outcome. It turns out that only bacteria that produce a toxin called cytolysin, which destroys host cells, exacerbates infections. The connection of E. faecalis and C. albicans positions the bacteria in contact with host cells, where its toxin wreaks havoc. Simultaneously, the yeast weakens host cells making them susceptible to the toxin. Knowing which strain of the bacteria is present in an infected patient could therefore inform how aggressive the treatment needs to be.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image from work by Mario Kapitan and colleagues, Ilse D. Jacobsen Lab, Leibniz-HKI
• Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany
• Image originally published with no restrictions – hence published here with as Creative Commons Attribution 4.0 International (CC BY 4.0)
• Research published in Proceedings of the National Academy of Science (PNAS), November 2025