U.S. health officials are warning clinicians across the country to be on the lookout for an emerging, highly fatal form of drug-resistant yeast that so far has killed two-thirds of those who’ve become infected.
While most people are familiar with garden variety yeast infections that can attack the skin and genitals, the new species of invasive yeast presents a completely new threat, especially for patients in intensive care or having surgery. Others at risk include people with diabetes, patients taking powerful antibiotics and antifungal medications, and those with catheters.
This emerging strain of yeast, Candida auris, has triggered outbreaks in health-care settings, causing bloodstream, wound and ear infections. Since 2009, the pathogen has been found in nine countries on four continents, including one possible infection in the United States in 2013.
The Centers for Disease Control and Prevention sent a clinical alert to U.S. health-care facilities and dozens of medical societies to share with their members. “CDC is concerned that C. auris will emerge in new locations, including the United States,” the alert said. The infections have most commonly been acquired in hospitals and occurred several weeks into a patient’s hospital stay.
Officials warn that the yeast doesn’t respond to common antifungal drugs and is difficult to identify with standard laboratory methods.
“What concerned us is that it is potentially resistant to one or two, if not all three” main classes of antifungal drugs used to treat these infections, said Tom Chiller, the CDC’s top fungus expert.
Based on information from a limited number of patients, 60 percent of people with this new type of Candida infection have died, but it’s not clear how many of them had other serious illnesses that also increased their risk of death.
Researchers say that drug-resistant fungi have arisen largely as a result of the use of fungicides on crops. Bacterial resistance is usually attributed to the use of antibiotics on farms and their overuse by doctors.
Scientists should be researching whether the widespread spraying of herbicides and pesticides contributes to antibiotic bacterial resistance as well.
Very little is currently known about C. auras — how well it adheres to the skin, how it colonizes the gut, where it comes from in the environment, etc. This unfamiliarity and uncertainty are making it especially difficult for physicians to identify.
While antibiotics are ineffective against this new pathogenic yeast, bacterial probiotics may offer some protection by maintaining the health and diversity of the gut microbiota. Yeast in the gut is typically kept in check by other organisms in the gut microbiota, but when that balance is thrown off by a course of antibiotics or other causes, bad yeast can get out of control and cause serious health issues. Saccharomyces boulardii, a non-colonizing yeast, and S. cerevisiae (brewer’s yeast) may help in warding off warding off harmful fungi and pathogenic yeasts, especially in patients who have recently taken antibiotics, which tend to kill off bacteria (but not yeast), thereby allowing the yeast population to explode.