The fungus Aspergillus fumigatus (in red) creates a sugar molecule (in green) that forms a protective shield around it called a biofilm, which it uses to deflect attacks from the body’s immune system and antimicrobial drugs. McGill University

Scientists are trying to stop drug-resistant fungi and bacteria by using their own kind against them.

A group of researchers have used two microorganisms that commonly cause lung infections to develop a treatment that breaks down the invaders’ protective shields, exposing them to a defensive attack from the body’s immune system. According to a study in the Proceedings of the National Academy of Sciences journal, the team discovered enzymes in the Pseudomonas aeruginosa bacterium and the Aspergillus fumigatus fungus that will weaken the biofilm surrounding them.

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That biofilm is a membrane microbes build around themselves that protects them from our white blood cells, the soldiers of the immune system. In the same way it deflects our body’s defenses, it also serves as a physical and chemical buffer against antibiotic and antifungal medications. It is “used by both bacteria and fungi to colonize surfaces and to enhance resistance to killing,” according to the study.

The scientists created enzymes that will break down the sugars forming the biofilms, using the ones in Pseudomonas aeruginosa and Aspergillus fumigatus as models.

Although the microbes build up this armor, they also produce enzymes that break down the sugars in their biofilms in order to move them around and reshape the armor. The scientists used that to their advantage, deriving a treatment from those enzymes that would break down the sugars to the advantage of the humans, rather than the microbes.

The result is a treatment that will “disrupt preformed fungal biofilms and reduce virulence,” the study says, as well as increase the effectiveness of antifungal drugs by helping them penetrate into the microorganisms to fight them off.

The enzyme treatment could be key to saving people in medical facilities in particular, as these drug-resistant microbes commonly infect hospital patients and are dangerous to those whose immune systems are compromised, according to McGill University. Bacteria and fungi can grow on human tissues as well as medical devices within the body like catheters and artificial hips, threatening these patients.

“Biofilm-associated infections are responsible for thousands of deaths across North America every year,” McGill said.

But the new treatment could treat numerous illnesses, from pneumonia to urinary tract infections. The new enzymes aim to prevent the microbes from forming their protective barriers and break down the ones they have already built, to make them easier to eradicate.

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“We were able to use the microbe’s own tools against them to attack and destroy the sugar molecules that hold the biofilm together,” researcher Don Sheppard, director of the Division of Infectious Diseases at the McGill University Health Center, said in the university statement.

“Rather than trying to develop new individual ‘bullets’ that target single microbes, we are attacking the biofilm that protects those microbes by literally tearing down the walls to expose the microbes living behind them. It’s a completely new and novel strategy to tackle this issue," Sheppard added.

One other advantage of the treatment is that an enzyme doesn’t just work on the bacterium from which it was derived. According to McGill, for example, bacteria enzymes will also work on fungi biofilms.

“We made these enzymes into an uncontrolled biofilm-destroying machine that we can use outside the microbe where the sugar molecules are found,” researcher Brendan Snarr said. “These enzymes chew away all of the sugar molecules in their path and don’t stop until the matrix is destroyed.”