How the US can stop the spread of Candida auris, a drug-resistant fungus

With potential vaccines still in development, prevention is key.

The Centers for Disease Control and Prevention (CDC) sounded the alarm earlier this week over the recent, rapid spread in health care facilities of a drug-resistant fungus that can cause deadly infections in immunocompromised individuals.

First discovered in 2009, Candida auris, or C. auris, has now been found in over half of US states. The number of infections rose 59 percent between 2019 and 2020 — and again by 95 percent in 2021 — to a total of 1,471 recorded cases, according to a paper released Monday.

While the fungus usually doesn’t pose a risk to healthy people, it is a risk to patients who are already very ill, particularly those in nursing homes and who have breathing tubes, feeding tubes, catheters, or other medical devices inserted in their bodies. Between 30 and 60 percent of people infected with the fungus have died, but that is based on a limited number of patients, and it’s unclear whether the fungus or another medical condition caused their death.

Candida auris seems to increasingly resist typical antifungal treatments called echinocandins. While researchers are trying to develop a vaccine targeting Candida auris and other common fungal infections, we’re years away from that potentially becoming a reality. For now, public health officials are focused on stopping the spread, which is difficult given just how persistent the fungus can be: It can spread person to person, living in their skin and body, but also via surfaces that it colonizes, such as furniture in a patient’s room, where it is resistant to many common disinfectants.

“It’s very sticky. It’s hardy in the environment,” said Scott Roberts, associate medical director of infection prevention at Yale School of Medicine.

How to prevent Candida auris from spreading

Roberts said that public health policy needs to be centered on improving lab infrastructure and screening protocols so that cases can quickly be identified and reported.

“The key is really being able to identify cases appropriately. And then once you identify them to isolate them or cohort those patients so they don’t spread it to other people,” he said.

One roadblock is that many labs aren’t equipped to identify Candida auris because they have older fungal libraries that cannot detect this particular new species. There have also been many cases of labs misidentifying the fungus as another species.

If medical professionals have a suspicion that a patient might have Candida auris, they typically have to send a sample to their state public health lab, which can take days to over a week to deliver a result. They should be isolating the patient and using the appropriate protective equipment and disinfectants in that period, as the CDC has recommended. But if they haven’t been doing so, the prospect of stopping further contagion becomes difficult.

Beyond building up lab capacity to identify cases, care providers need to enact stricter protocols to test and limit exposure to individuals who are at high risk for infection. Roberts said he’s previously worked at a facility that proactively screened patients who had been on ventilators, were coming from nursing homes, or had recently traveled internationally and found cases that would have never otherwise been identified. That’s not really being done in most parts of the country right now, he said.

“You have to have some sort of active surveillance mechanism where you can identify those at high risk when they get to the hospital or in whatever facility they’re at if it’s a high-prevalence region. I think that’s the best strategy we have right now to stop the spread,” he said.

Stopping the spread is critical because a Candida auris infection can be very difficult, if not impossible, to treat. Even when antifungals are effective against it, those drugs can be harsh on the liver. And when the drugs don’t work, the fungus can live in the body for years — or even indefinitely.

Will a vaccine for Candida auris become available?

We don’t currently have any vaccines for fungal infections, and as my colleague Keren Landman writes, “it’s not for lack of trying.” But the researchers working on preventive measures say that the rapid spread of Candida auris adds urgency to the mission for a drug-resistant fungal vaccine moonshot.

“There needs to be a vaccine. And it needs to be supported right now,” said Karen Norris, an immunologist at the University of Georgia’s veterinary school, who leads a team developing a potential fungal vaccine.

With the support of the National Institutes of Health, her team is designing a fungal vaccine to be cross-protective against several different fungal pathogens, potentially including Candida auris. They demonstrated in a paper published last year that the vaccine will induce an immune response in animals and particularly those that are immunosuppressed or immunocompromised.

They have yet to test it on humans. A phase one clinical trial would still be more than a year away, and that’s assuming they have the funding to undertake it.

“We are looking at the process for scaling up the manufacturing of this vaccine for development and for safety studies down the road in people,” Norris said. “We are hoping to partner [with the private sector] to advance this at a more rapid pace than where we are right now.”