Researchers in the U.S. and India are investigating the potential of some probiotic yeasts to prevent and treat serious drug-resistant fungal infections.
Probiotics are live bacteria and yeasts that can be beneficial for health. Probiotic organisms are found in some foods, such as yogurts, and are also produced as food supplements. They have been shown to improve digestive system health and may have many other health benefits including treatment of allergies, type 2 diabetes, and prevention of some infections. Researchers at Worcester Polytechnic Institute, Massachusetts, U.S., and the Central Food Technological Research Institute, Mysore, India are investigating the potential of certain probiotic yeasts to prevent life-threatening fungal infections in hospital patients. They recently published their research in mBio.
Fungal infections in immunocompromised and hospital patients
Candida albicans is the leading cause of fungal infections in hospital patients, but non-albicans Candida species are of increasing concern to doctors as they also cause severe infections and many strains do not respond to antifungal drugs. These types of fungal infections are a particular problem in patients with weakened immune systems or hospital patients who have implanted medical devices, catheters, or intravenous drip lines. Even when antifungal drugs work, they can have serious side effects as they may damage human cells and tissues. Some probiotic food-derived yeasts could offer an alternative way of preventing or treating non-albicans fungal infections.
Probiotic yeasts preventing pathology
Some of the characteristics thought to allow non-albicans fungi to cause infection and resist drug treatment are their abilities to adhere to surfaces and to form “biofilms”, which become a physical barrier against antifungal drugs. In a series of laboratory experiments, the researchers looked at whether certain probiotic yeasts can stop the adhesion and biofilm formation of non-albicans Candida species on non-biological surfaces (similar to materials in catheters and intravenous lines) and on human gut cells.
In one set of experiments, they found that applying probiotic yeasts to non-biological plastic surfaces reduced the adherence of non-albicans Candida by up to 53%, and reduced biofilm formation by up to 70%. In other experiments, they showed that probiotic yeasts could reduce the adhesion of non-albicans Candida to human gut epithelial cells.
To test whether any effects would be observed in living organisms, the researchers studied nematode worms, which have some similar key features to the human intestinal system. They found that nematodes pre-treated with probiotic yeasts were protected from infection by non-albicans Candida compared with non-treated nematodes. In addition, giving probiotic yeasts to nematode worms after they were infected with non-albicans fungi alleviated the gut infection.
An alternative treatment for drug-resistant fungal infections
These laboratory investigations suggest that certain probiotic yeasts could provide an effective alternative to antifungal drugs in preventing and treating non-albicans Candida infections.
“As the rate of deadly infections by … non-albicans fungi species increases, there is a pressing need for more effective and safer medications to both prevent and treat these intractable illnesses,” said Prof. Reeta Rao, one of the lead authors of the study. “This study has shown that probiotic yeast may be the alternative we have been looking for, and certainly warrants further investigation,” she added.
- Kunyeit L, Kurrey NK, Anu-Appaiah KA, et al. Probiotic yeasts inhibit virulence of non-albicans Candida species. mBio Doi:1128/mBio.02307-19. Published online 15 October, 2019.
- Worcerster Polytechnic Institute, Press release 10 Dec, 2019. “Probiotic yeast may offer an effective treatment for drug-resistant fungal infections. https://www.eurekalert.org/pub_releases/2019-12/wpi-pym121019.php