A study by researchers in the United States and India has shown that probiotic yeasts derived from food are able to reduce the virulence of, and even prevent infections by, several types of fungi that are responsible for life-threatening infections in hospitalized and immune-compromised individuals, including the multi-drug resistant Candida auris, which was recently listed as an urgent threat by the U.S. Centers for Disease Control in its 2019 Antibiotic Resistance Threats report.
While Candida albicans is the leading cause of hospital-acquired fungal infections, the study focuses on a number of non-albicans species that are of increasing concern to public health officials as they can cause similar infections and as many of these strains are developing resistance to available antifungal medications.
Reeta Rao, professor of biology and biotechnology and associate dean of graduate studies at Worcester Polytechnic Institute (WPI) and one of the lead authors of the study, explained, “Candida auris, for example, which can cause severe, often fatal infections in hospitalized patients, frequently does not respond at all to commonly used antifungal drugs, making infections almost impossible to treat.”
In immune-compromised patients or even healthy individuals with implanted medical devices, Candida can penetrate the submucosal tissue of the gastrointestinal tract and reach the internal organs, where it can cause life-threatening systemic infections. The microbes’ drug resistance stems, in part, from their ability to adhere to surfaces and form biofilms. “A biofilm is a complex ecosystem that can become a physical barrier against drugs,” Rao said. “Biofilms can form on medical devices, catheters and IV lines, and even contact lenses. They can also penetrate epithelial tissue in the body, leading to a variety of infections, including the deadly bloodstream infections we can see with Candida auris.”
Even when they do work, antifungal drugs often have serious side effects. Fungal cells are similar to the eukaryotic cells that make up human bodies, so the drugs can attack and damage the very tissues they are designed to protect. “This has led to a growing recognition of the need for alternative therapies,” Rao said. “We chose to look at food-derived probiotic yeast, which could present a safe and cost-effective method to keep Candida in check.”
