Jhe US Centers for Disease Control and Prevention (CDC) is monitoring the rise of a deadly treatment-resistant fungus that is causing outbreaks in a growing number of health care facilities across the country.
New data compiled by a CDC research team, published March 21 in Annals of Internal MedicineAC watch candida auris infections have increased dramatically in the United States in recent years. In 2021, national cases reported by health facilities increased by 95%, and from 2019 to 2021, 17 states reported their first case. With infections recorded in a total of 28 states and the District of Columbia, these numbers suggest that current disinfection and safety measures in healthcare settings may not be enough.
Experts do not currently see C.auris as much of a threat to the general population, since most healthy people are not at risk of serious infections, which tend to spread in hospital settings. But there are fears that it could one day evolve into one.
The first American case of C.auris the infection was reported in 2016, and although travel later brought it to a number of states, “at first we didn’t see such a dramatic increase,” says Meghan Lyman, a physician at CDC Mycotic Disease Branch and first author. On paper. “It gave us some hope.” Things changed in 2019, she says, when an influx of states reporting outbreaks made it clear the threat was here to stay. “We realized it’s just a really fragile situation.” A study 2022 describes a simultaneous increase in European epidemics, and the CDC says that infections have occurred in more than 30 countries worldwide since the fungus first appeared in Japan in 2009.
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The new findings may also reflect the impact of the COVID-19 pandemic. In 2020, eight states reported their first cases of C.auris, more than any other year. CDC scientists believe that crowded conditions in hospitals, especially those facing shortages of staff, equipment and PPE, have contributed to the spread of the fungus. Infections are rare but serious—mortality rates are around 30%– and symptoms may include fever and chills, followed by organ failure.
Most fungal infections, mild or severe, are caused by one of hundreds of types of candidiasis yeasts. Some types of candidiasis live peacefully in our body – a yeast infection, for example, is simply an overgrowth of one of these helpful species. C.auris is one of the most dangerous types, but for most healthy people, the fungus will temporarily colonize the skin without causing illness or harm; without testing, you would probably never know it was there. This type of colonization often resolves naturally, thanks to the fungi present in the normal skin flora which eventually rebalance themselves and take over. The danger arises when C.auris finds its way into the body through a wound or other opening, especially if someone is weakened or immunocompromised.
This helps explain why CDC data comes almost entirely from health care facilities. Another factor is that people who are already in these settings are more likely to be tested for it, following a bad infection or death. “When the first case comes up, it’s often a clinical case because people might not be looking for it,” Lyman says. If you go to the hospital and you fear an infection, “you can always ask, as soon as you enter, if they do a screening C.auris“, explains Johanna Rhodes, researcher at Imperial College London (who was not involved in the study). In an ideal world, she says, hospitals would screen all patients as they enter. While no state yet requires hospitals to test this extensively, several have either recommended he or undertaken county-level projects to make widespread screening more feasible.
Most fungi capable of infecting humans pose threats to certain body systems. Some can infect the lungs, others the skin, and some even seem to affect Mental Health. This particular species of candidiasis affects blood circulation and infections such as those caused by C.auris, “are similar to sepsis,” says Rhodes. “But it’s harder to treat.”
C.auris is resistant to antifungal drugs, which makes it unique among fungi. “If you look at all the species of candidiasisonly about 7% of all isolates [individual cell samples trapped and regrown in a lab] are resistant to antifungals,” says Shawn Lockhart, director of the CDC’s Fungal Reference Laboratory and author of the paper. “Now all of a sudden we have this bug where 85-90% of all isolates are resistant.”
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Generally, a drug-resistant fungus can escape one of the three main types of antifungal drugs. But C.auris is pan-resistant, which means that all three treatments are weakened or ineffective against it. Scientists also tracked the drug resistance of C.auris over time, and the fungus has evolved dramatically in a short time, which worries experts. “I can only think of another report from a pan-resistant candidiasis,” he says. “The difference is that he was never resistant to all three antifungals at the same time.”
C.auris also has an unusual ability to stick around. The fungus is able to form biofilms, Rhodes explains, “which is basically like having an Iron Man armor or suit. That allows it to persist in the environment, it makes it super sticky to surfaces, and it can resist disinfectant. 2015 studyRhodes discovered that C.auris was resistant to most disinfectants used by the UK national health system at the time and prompted the recommendations to be adjusted. This “adhesion” allows C.auris to latch onto medical equipment like ventilators and catheters in a way that other infectious agents cannot.
To help reverse the rise of the fungus, the first step should be to find a way to reduce the amount of C.auris that patients harbor, Lockhart says. “The key is to reduce colonization enough that it doesn’t spread to other patients, to protect those most at risk.” Doing this first requires minimizing the spread, which she says can be done by properly maintaining sterile hospital environments and cleaning procedures.
Lyman is confident that steps can be taken to slow the spread and reduce the number of cases in the United States. “We actually saw many installations in areas that prevented and even stopped transmission,” she says. The key, she says, will be “really strong infection control and good communication.”
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