Scientists zero in on the life-threatening fungus, Candida auris' ability to stick

A weird fungus that preyed on the weakest among us appeared out of nowhere in 2009. Although it seems like something out of Hollywood, the fungus in issue is a real concern. Researchers are working feverishly to determine what causes the deadly fungus Candida auris to proliferate and why hospitals and other care environments frequently struggle to eradicate it despite their best efforts at infection control.

Focusing on C. auris' remarkable capacity to adhere to surfaces such as skin and catheters, researchers at the University of Michigan have uncovered an astonishing finding. According to the publication "A Candida auris-specific adhesin, SCF1, governs surface association, colonization, and virulence," it is published in Science.

The U-M Medical School Department of Microbiology and Immunology's Teresa O'Meara, Ph.D., and her graduate student Darian Santana lead the investigative team that has found that C. auris differs from all other known fungi in that it uses an adhesin, a type of protein that functions very similarly to those used by oceanic organisms like mollusks and barnacles.

Initially, they thought that Candida auris would utilize an adhesin from the sticky protein family that Candida albicans and other fungus employ. IFF4109 was the only protein that showed a partial effect when they examined the usual suspects, which are proteins from the highly conserved ALS and IFF/HYR families.

After that, they switched to a different screening technique to methodically disrupt the C. auris genome and observe which mutant was unable to adhere to 96-well plastic plates. This allowed them to identify a novel adhesin that they called Surface Colonization Factor (SCF1).

Since the novel adhesin is exclusive to C. auris, its evolutionary origins are unknown. By sequence similarities, it doesn't appear to have originated from any other creatures," O'Meara stated. They discovered that Scf1 created cation-pi bonds, which are some of the most powerful non-covalent chemical connections seen in nature.

O'Meara continued, saying, "People trying to bioengineer glue that sticks underwater have produced a large amount of the literature regarding this sort of binding in nature. As a result, they have drawn inspiration from nature."

Moreover, the group found that SCF1 was linked to higher colonization and a greater capacity for illness. They showed, using animal models, that a strain of C. auris was less able to colonize skin and an indwelling catheter when both SCF1 and IFF4109 were lost. Furthermore, bacteria engineered to overexpress SCF1 exhibited increased fungal lesions and increased pathogenicity.

O'Meara stated, "We don't know why this adhesin is necessary to cause disease." "We don't know in this case whether they are necessary to attach to blood vessels or if they alter the host-receptor interactions, as has been observed for the related fungus Candida albicans."

Since many C. auris strains are resistant to existing treatments, O'Meara and her team intend to look into the relationship between SCF1 and virulence in the hopes of using it for a more effective anti-fungal therapy. The adhesin's barnacle-like adhesive qualities point to a marine origin, which might offer scientists insight into the origins of C. auris.

"In contrast to SARS-CoV2, which only arose in one site, C. auris came out of nowhere in five different places worldwide. The planet saw a shift in selection pressure that made C. auris transition from being completely harmless to invading human populations."