SYDNEY: An antimicrobial compound produced in wallaby milk could be a new weapon in the continuing battle against antibiotic-resistant superbugs, say researchers conducting pre-clinical trials.
This is one of a number of compounds recently found in marsupials, such as koalas, that have exciting medical applications. Young wallabies don’t develop an immune system until 100 days after birth, yet they typically manage to avoid infection. This compound is part of the reason why, say Australian scientists.
The compound, employs a unique mechanism to rapidly kill bacteria. And it may work against some of the most dangerous multidrug-resistant pathogens – such as vancomycin-resistant Enteroroccus, which poses a particular threat to patients with compromised immune systems and Pseudomonas.
Using advanced computer systems, researchers at the state of Victoria’s Department of Primary Industries in Melbourne, Australia, found more than 30 potential bug-fighting compounds in the milk of the Tammar Wallaby (Macropus eugenii). One compound, known as AGG01, was particularly potent said lead researcher and animal geneticist, Ben Cocks.
Some experiments showed small amounts of a synthetic form of the drug were able to kill all bacteria in 30 minutes. “We found in lab tests that AGG01 is very effective against multidrug-resistant gram negative bacteria, including those that are most difficult to treat,” he said.
The compound is termed a ‘broad-spectrum antimicrobial’ because it is useful in the treatment of many bacterial and fungal pathogens. Antimicrobial agents include antibiotics, as well as synthetically devised compounds that can kill or prevent the growth of pathogens. Broad spectrum antimicrobials, such as vancomycin, are typically used as a last resort for treating infection, to reduce the chance of bacteria becoming resistant, and also because they can have serious side effects.
AGG01 is effective because it works rapidly and kills bacteria rather than just preventing their growth, said Cocks. It also uses a novel method to kill bacteria, which may involve striking at the bacterial membrane, but more research is needed to confirm this.
“We know it is a unique mechanism, since it works against some clinical isolates resistant to all available antibiotics,” he said. “Theoretically, it is going to be hard for the bacteria to develop a resistance [to AGG01], since the membrane is essential.”
Cocks is part of a team who presented a talk on the new compound this week at the BIO2007 conference held in Boston, U.S..
The next step is to determine if the compound will be safe for use in humans. Laboratory tests already indicate that it is not toxic to human tissue, he said.
This is one of many compounds with exciting medical applications being discovered in marsupial milk, commented Elizabeth Deane, a marsupial immunologist at Macquarie University in Sydney. “Marsupials are born after a very short gestation period and have no immune system of their own, so a whole suite of maternal strategies are needed to protect the young,” she said.
She added that maternal pouch secretions and skin secretions from the newborn itself might also have antimicrobial properties. Deane herself has found a number of antimicrobial compounds in koala pouch secretions.
Ben Cocks’s web site