Rise in fungal infections illustrates risks of antimicrobial resistance

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Silvia Corcione had a nagging suspicion about a patient who kept on developing fevers, no matter what therapies her infectious-disease team administered.

“We knew he was infected with Candida [a fungus], but we did not know which species,” recalls Corcione, a doctor at Turin’s City of Health and Science hospital. She worried about the infection spreading through the hospital while tests were carried out.

It was eventually established that the species was Candida auris, which is often drug-resistant and has spread across the world since first being identified in Asia in 2009. It was also the first time Corcione encountered it. Antifungal therapy managed to clear the infection, but the patient still died because of other clinical factors.

This episode shows the growing danger of antimicrobial drug resistance, which is now found not just with bacteria but also viruses, fungi and parasites.

Candida auris is usually not a threat to healthy people, and can live on the skin without causing an infection.

But it is dangerous for those in poor health. It mainly spreads in healthcare facilities among people with severe health problems. About one in three of those who contract it pass away. In March, the US Centers for Disease Control issued a warning saying it ­classified the pathogen as an “urgent” threat.

“The rapid rise and geographic spread of cases is concerning and emphasises the need for continued surveillance, expanded lab capacity, quicker diagnostic tests, and adherence to proven infection prevention and control,” said Meghan Lyman, a CDC epidemiologist, at the time.

Candida auris is also on the World Health Organization’s list of priority pathogens. Last year, it said that there were “only four classes of antifungal medicines currently available, and few candidates [are] in the clinical pipeline. Most fungal pathogens lack rapid and sensitive diagnostics and those that exist are not widely available or affordable globally”.

The consequences of poor drug prescribing practices and lack of diagnostics were demonstrated during the Covid-19 pandemic in India. The overprescription of steroids, which weaken the immune system, to treat Covid led to a swell of cases of “black fungus” or mucormycosis. This starts in the nose and quickly spreads to the eyes and brain, and has a high fatality rate. Drugs to treat it were in short supply and the WHO had to step in, calling for supplies to be boosted and prices to be lowered.

Javier Guzman, the director of global health policy at the Center for Global Development, says that medics “who are at the frontline normally don’t see a lot of fungal infections, because there’s no awareness and there’s no testing and you get to [diagnosing] it after many rounds of misdiagnosis”. He warns: “It’s not so much the future [threat] as it is the present. But clearly, this is only going to increase.”

He explains that part of the problem is the rise of highly effective and potent drugs that suppress immune system activity in patients for whom there is a benefit, but which also have the unintended consequence of making them a potential host for fungi that would normally not pose a threat.

Another issue, which he acknowledges is not yet measured, is the rise of climate change. “It’s known that, in warmer more humid climates, you do have more infections, you do have more resistance, you do have more of the right environment for infections to thrive.”

As with most health policy issues, the key is to shift from short-term to long-term thinking, he argues — for example, by focusing on accurate diagnostics and effective treatments that address fungi not seen before. “It’s about looking at fungal infections like a neglected issue,” he suggests. “The armamentarium [treatment range] is not growing, it’s actually shrinking because of the resistance issue.”