Platypus Milk: Antibiotic Resistance Weapon May Lie in Animal's 'Weird Biochemistry'

The World Health Organisation calls antibiotic resistance one of the "biggest threats" to global health today. As antibiotics become less effective against infections, mortality rates and medical costs are rising.

The latest contender in the fight against resistance comes from an unlikely source—the humble platypus.

Platypus are known for their beaver tails, their venomous spurs and, of course, their big, duck-billed snout. The Australian egg-laying critters are less known, however, for their antibacterial milk.

A platypus hanging out. The creature's milk contains a uniquely-structured protein that could be a weapon against antibiotic resistance. Laura Romin/Larry Dalton/CSIRO

"Platypus are such weird animals that it would make sense for them to have weird biochemistry," said Janet Newman, lead author of a new study into the animal's milk published in Structural Biology Communications, in a statement.

Read more: Forgotten Antibiotic Could Save the World From Deadly Superbugs

Platypus milk was shown to have antibacterial properties back in 2010. Now, scientists from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Deakin University in Victoria, Australia, have discovered why the milk is so powerful. This new evidence, researchers hope, will one day improve antibacterial dressings and creams.

Platypus are members of the monotreme family of mammals that lay eggs and make milk for their young. Unlike animals like dogs, cats and cows—and humans, for that matter—who feed their babies straight from the teat, platypus express milk onto their bellies. The milk is exposed to the bacteria-filled world outside before babies get a chance to drink.

Researchers think this is key to the milk's unusual antibacterial characteristics.

3_15_Shirley Temple Protein structure
A map of the Shirley Temple protein fold. Researchers named after the child star's ringlets. CSIRO

"By taking a closer look at their milk, we've characterised a new protein that has unique antibacterial properties with the potential to save lives," said Newman, who is a scientist at CSIRO.

Read more: There's an Antibiotic Apocalypse That's Going to Send Us Back to the Dark Ages of Medicine

Scientists mapped the unique protein to unlock its secrets. "We were interested to examine the protein's structure and characteristics to find out exactly what part of the protein was doing what," explained Deakin University's Julie Sharp explained in the statement.

The team discovered the protein structure had a never-before-seen 3-D fold. They dubbed it the "Shirley Temple" for its curling ringlets. The find, Newman said, was pretty special, and will drive future drug discovery in the battle against superbugs.

"Although we've identified this highly unusual protein as only existing in monotremes, this discovery increases our knowledge of protein structures in general, and will go on to inform other drug discovery work done at the Centre," she said.