In the fight against drug-resistant bacteria, researchers at McMaster University in Hamilton are enlisting an unexpected army: ants, bees and beetles.
These tiny creatures could hold the key to discovering groundbreaking new antibiotics and outsmarting antimicrobial resistance, also known as superbugs.
That’s because insects like leafcutter ants have figured out a clever trick: they grow fungal gardens for food, and in return, they’ve formed a symbiotic partnership with bacteria that produce powerful antimicrobial chemicals to protect their crops.
This eons-old relationship, now being studied by a team at McMaster University, could offer a way to help battle against antimicrobial resistance.
“These ants are amazing organisms. They cut leaves and they use that leaf material to grow a fungus for food,” explained Cameron Currie, lead researcher and a biochemistry and biomedical professor at McMaster University. “And so they’re performing what’s the equivalent of human agriculture, they’re growing their own food source, and that’s what they use to feed and rear their young.”
However, these ants face a significant challenge: fungal diseases that threaten their fungus gardens. To overcome this, the ants have evolved to harbour bacteria that secrete antimicrobial substances, keeping their crops disease-free.
The bacteria get a nutrient-dense place to live, and the ants get disease-free crops, creating what Currie calls a “symbiosis.” And this relationship, he said, could inspire new approaches to addressing the growing issue of antimicrobial resistance in humans.
A growing global health crisis
Antimicrobial resistance is one of the top global public health and development threats, according to the World Health Organization.
It happens when bacteria, viruses, fungi and parasites become resistant to the medications we rely on to treat infections. This means that illnesses that were once easily treatable, like pneumonia or tuberculosis, could become much harder, or even impossible, to cure.
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“So antimicrobial resistance, the situation where the pathogens that attack humans are evolving resistance to antibiotics we’re using to treat them, is a major problem,” Currie said.
“One of the things that we need to do is discover new chemicals, new antibiotics to treat those infectious diseases that these bacteria and fungal pathogens of humans haven’t had a chance to evolve resistance to. So we need new antibiotics.”
Antibiotics used to treat infections come from bacteria found in the soil, which scientists study and develop into drugs, Currie explained. Similarly, ants, along with other insects, use related bacteria to produce antimicrobials. His team is now focusing on studying these bacteria from ants to explore their potential for new antibiotics.
So far, the McMaster team’s research has identified more than 10 new antimicrobial substances from these bacteria on ants, with some showing promise in preclinical testing, especially for treating fungal infections.
The ants used in these tests come from all over the world, including places like Costa Rica and Brazil. Researchers travel to these locations to collect the ants, isolate the bacteria, and bring both the ants and their colonies back to the lab in Hamilton to examine.
Other insects are involved in their research too, such as bees, wasps and beetles.
Julian Rosati, a second-year bio-chem undergrad at McMaster University, has been working on bees, and said being a part of the research has been an eye-opening experience.
“It’s taught me that we don’t need to look in the craziest of places to find new antibiotics because they might be right here places you wouldn’t expect to look,” he said.
The team has discovered antimicrobials that are highly effective against bacterial infections, but Currie noted that the most promising compounds are those targeting fungi.
“There’s an increasing issue with fungal disease as fungi are somewhat closely related to humans. So we have very limited antimicrobials or antifungals to treat fungal diseases,” Currie said. “And there’s a lot of concern around Candida auris, this emerging, multidrug-resistant fungal disease spreading and throughout the world is a major threat.”
The fungal infection has proved deadly, especially for those with compromised immune systems, and has demonstrated an ability to spread easily in health-care settings.
Currie and his team are hopeful that their new antimicrobial compounds could lead to innovative treatment options. The next step, he explained, is to test whether these compounds can effectively treat human diseases in a mouse model.
“We have a number of molecules from the ants that have shown what we call efficacy. So effectiveness in a mouse model and also safety. And that’s a really important step in moving something closer to the clinic.”
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