Author Arturo Casadevall explores why outbreaks of drug-resistant C. auris have become inevitable. (Image credit: Shutterstock)
Fifteen years ago, scientists identified a new species of deadly, drug-resistant fungus: Candida auris. It is now considered one of the most threatening fungal pathogens on the planet. In this excerpt from What If the Fungi Win? (Johns Hopkins University Press, 2024), author Arturo Casadevall examines the spread of this dangerous fungus, which may be the first to emerge as a result of climate change.
In 2009, doctors at a Japanese hospital published a paper describing a new type of fungus found in the ear canal of a 70-year-old patient. They named it Candida auris, where auris is the Latin word for ear.
At first, it was unclear how seriously, if at all, this new discovery should be taken. Every year, many new fungal species are detected in patients, but the vast majority of them turn out to be isolated cases that cause no cause for alarm.
C. auris flew under the radar for a while, remaining a little-known yeast in most parts of the world — until it was identified in hospitalized patients around the globe, all at roughly the same time. Surprisingly, between 2012 and 2015, doctors in South Africa, Venezuela, and the Indian subcontinent simultaneously reported treating patients suffering from what turned out to be C. auris infections (remember, no one knew about this type of fungus just a few years ago).
With no connections or common features, these cases of C. auris arose independently on three different continents, with each fungus genetically distinct from the others.
This meant that the usual suspect for the spread of the fungus—our globalized world—was not involved. Something new was growing. It quickly became apparent that this fungus was remarkably resistant to treatment. More than one in three patients with invasive C. auris infections in their blood died. In hospitals where this invasive fungal disease had not previously been seen, it became a significant cause of death.
Today, C. auris is largely resistant to the antifungal drugs we have, so once patients (and hospitals) become infected, it’s nearly impossible to get rid of. Doctors typically diagnose fungal infections after ruling out other sources, such as when a hospitalized patient has a fever that doesn’t go away with antibiotics. Blood tests will likely show elevated white blood cell counts, another sign of infection, but doctors often can’t determine what type of germ is causing the damage or know how to treat it.
Symptoms vary depending on the type of fungus. Cryptococcus neoformans typically affects the brain and causes severe headaches. Aspergillus typically affects the lungs, causing patients to cough, become short of breath, and may show what appears to be pneumonia on a chest X-ray.
Fungi that cause illness can enter the body through inhalation or through cuts and wounds; infections can spread in hospitals through poorly maintained intravenous lines and catheters. The most common symptoms are fever, malaise, or just a general feeling of being unwell. In hospitals where C. auris has been found, it has mostly spread among immunocompromised patients — despite the fact that person-to-person transmission is rare for the invasive fungus.
That may be because doctors have found that it can colonize human skin, remain on surfaces for weeks, and withstand the strong disinfectants used in hospitals. Some hospitals have reported that C. auris spores remain in patient rooms long after a patient has been discharged or died, even after other types of fungi have been killed by cleaning products. C. auris isn’t just staying outside hospitals.
By 2016, the U.S. Centers for Disease Control and Prevention (CDC) issued an alert to health care workers and laboratories urging them to be vigilant
Sourse: www.livescience.com
