We desperately need to find new antibacterial substances if we’re going to survive the era of resistant superbugs. With that in mind, researchers at the University of Technology Sydney’s ithree institute have been investigating the germ-killing properties of honey.
Their latest study, published last week in PLOS ONE, shows that Australian manuka-like honey can kill bacteria—even antibiotic-resistant ones—as effectively as the more famous New Zealand variety.
Manuka honey is special because it’s produced from the nectar of Leptospermum scoparium tree blossoms, and contains high levels of the antibacterial compound methylglyoxal (MGO). The lucrative New Zealand export product is known worldwide, but it turns out that Australia boasts several Leptospermum species capable of producing a similarly remarkable honey.
A Leptospermum tree in full bloom.
PHOTO COURTESY UTS ITHREE INSTITUTE
Knowing this, the researchers obtained samples of various local Leptospermum honeys and compared them to a manuka sample sent over from New Zealand. They measured the MGO levels and also pitted the honey samples against staph bacteria in a petri dish.
"What we found is that the [antibacterial] activity is very comparable", says Cokcetin. "It's really exciting that we can show we have Australian manuka that's at least as good as the New Zealand cousin."
Cokcetin’s study has been funded by the Rural Industries Research & Development Corporation, and the newfound superpowers of local honey are welcome news to the Australian bee industry, which is still free from the devastating impacts of the varroa mite.
"I was actually pretty surprised that the activity had remained so stable over that period time”
Furthermore, the antibacterial activity in the honey samples remained virtually unchanged for seven years, from when the honey was first collected and tested. The samples were stored in dark containers at a stable temperature of 4°C, and upon re-testing Cokcetin was excited to discover time hadn’t made a dent in their antibacterial powers.
"I was actually pretty surprised that the activity had remained so stable over that period of time,” she says. “We knew that it would be stable, but not to that degree because we expected it to lose some potency.”
To her, it’s a sign that medicinal honey could one day have a huge advantage over other antibiotics, which cannot be stored for such long periods without loss of efficacy.
However, it’s a long way to go until we might actually have honey-based antibiotics, warns Peter Collignon, Professor of Microbiology at the Australian National University.
“Basically I think it’s good news,” he says of the study, but emphasises that human trials are vital for any medicinal product.
“There’s no doubt honey can have antibacterial activity, but the real crunch is what happens when you use it in people, because you can’t just rely on test tube experiments.”
The researchers tested 80 samples of locally harvested honey.
PHOTO COURTESY UTSITHREE INSTITUTE
Honey is much loved in alternative and complementary medicine circles, but it pays to remember that just because it has antibacterial properties, it doesn’t mean you can simply eat some to treat an infection. And we still need more information for it even as a wound treatment.
“We don't fully know what its mechanism of action is,” says Cokcetin. “We know that it kills any bacteria that we put it in contact with [..] but we don't know exactly what it's doing.”
However, their previous work has shown that bacteria don’t develop a resistance to honey. That’s quite remarkable, considering the sweet stuff has been around for millennia—and excellent, considering its recent emergence as a potential new antibiotic.
"One of the projects that we're working on is to find out what the honey is doing to the bacteria so that we can better understand not only how honey works, but to use that in the future to help develop better antibiotics.”