One of the scariest things you can be told when at a doctor’s office is “You have an antimicrobial-resistant infection.” That means the bacteria or fungus making you sick can’t be easily killed with common antibiotics or antifungals, making treatment more challenging. You might have to take a combination of drugs for weeks to overcome the infection, which could result in more severe side effects.
Unfortunately, this diagnosis is becoming more common around the world.
The yeast Candida auris has recently emerged as a potentially dangerous fungal infection for hospital patients and nursing home residents. First discovered in the late 2000s, Candida auris has very quickly become a major health challenge due to its ease of spread and ability to resist common antifungal drugs.
How did this fungus become so strong, and what can researchers and physicians do to combat it?
I am a microbiologist researching new ways to kill fungi. Candida auris and other fungi use three common cellular tricks to overcome treatments. Luckily, exciting new research hints at ways we can still fight this fungus.
Drug-resistant Candida auris infections are on the rise in the U.S. and around the world.
Targeting the sensitive parts of fungal cells
Fungal cells contain a structure called a cell wall that helps maintain their shape and protects them from the environment. Fungal cell walls are constructed in part from several different types of polysaccharides, which are long strings of sugar molecules linked together.
Two polysaccharides found in almost all fungal cell walls are chitin and beta-glucan. The fungal cell wall is an attractive target for drugs because human cells do not have a cell wall, so drugs that block chitin and beta-glucan production will have fewer side effects.
Some of the most common drugs used to treat fungal infections are called echinocandins. These drugs stop fungal cells from making beta-glucan, which significantly weakens their cell wall. This means the fungal cell can’t maintain its shape well. While the fungus is struggling to grow or is breaking apart, your immune system has a much better chance of fighting off the infection.
How fungi become drug resistant
Unfortunately, some strains of Candida auris are resistant to echinocandin treatment. But how does the fungus actually do it? For decades, scientists have been studying how fungi overcome drugs designed to weaken or kill them. In the case of echinocandins, Candida auris commonly uses three tricks to beat these treatments: hide, build and change.
The first trick is to hide in a complex mixture of sugars, proteins, DNA and cells called a biofilm. Made with irregular 3D structures, biofilms have lots of places for cells to hide. Drugs aren’t good at penetrating biofilms, so they can’t access and kill cells deep inside. Biofilms are especially problematic when they grow on medical equipment…