Killing superbugs with star-shaped polymers, not antibiotics

September 13, 2016 by Anne Rahilly, University of Melbourne
Killing superbugs with star-shaped polymers, not antibiotics
Engineering finds new ways to conquer superbugs. Credit: University of Melbourne

Tiny, star-shaped molecules are effective at killing bacteria that can no longer be killed by current antibiotics, new research shows.

The study, published today in Nature Microbiology, holds promise for a new treatment method against antibiotic-resistant (commonly known as superbugs).

The star-shaped structures, are short chains of proteins called 'peptide polymers', and were created by a team from the Melbourne School of Engineering.

The team included Professor Greg Qiao and PhD candidate Shu Lam, from the Department of Chemical and Biomolecular Engineering, as well as Associate Professor Neil O'Brien-Simpson and Professor Eric Reynolds from the Faculty of Medicine, Dentistry and Health Sciences and Bio21 Institute. Professor Qiao said that currently the only treatment for infections caused by bacteria is .

However, over time bacteria mutate to protect themselves against antibiotics, making treatment no longer effective. These mutated bacteria are known as 'superbugs'.

"It is estimated that the rise of superbugs will cause up to ten million deaths a year by 2050. In addition, there have only been one or two new antibiotics developed in the last 30 years," he said.

Professor Qiao and his team have been working with peptide polymers in the past few years. Recently, the team created a star-shaped peptide polymer that was extremely effective at killing Gram-negative bacteria – a major class of bacteria known to be highly prone to antibiotic resistance – while being non-toxic to the body.

In fact, tests undertaken on red blood cells showed that the star-shaped polymer dosage rate would need to be increased by a factor of greater than 100 to become toxic. The star-shaped peptide polymer is also effective in killing superbugs when tested in animal models.

Furthermore, superbugs showed no signs of resistance against these peptide polymers. The team discovered that their star-shaped peptide polymers can kill bacteria with multiple pathways, unlike most antibiotics which kill with a single pathway.

They believe that this accounts for the superior performance of the star-shaped peptide polymers over antibiotics. One of these pathways includes 'ripping apart' the bacteria cell wall. (see image). While more research is needed, Professor Qiao and his team believe that their discovery is the beginning of unlocking a new treatment for antibiotic-resistant pathogens.

Explore further: Understanding drug-resistant superbugs

More information: Shu J. Lam et al. Combating multidrug-resistant Gram-negative bacteria with structurally nanoengineered antimicrobial peptide polymers, Nature Microbiology (2016). DOI: 10.1038/nmicrobiol.2016.162

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8 comments

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TogetherinParis
1 / 5 (1) Sep 13, 2016
Similar to diatomaceous earth's attack against bed bugs.
tekram
5 / 5 (1) Sep 14, 2016
Much better article elsewhere:

"A PhD student at Melbourne University has developed a star-shaped protein that can rip apart the walls of resistant superbugs – and kill them. Shu Lam, 24, has had her research published today in the prestigious Nature Microbiology journal.

Ms Lam has designed her protein chains in star shapes with 16 or 32 arms that are about 10 nanometres in diameter, much larger than other antimicrobial peptides.

Professor Greg Qiao is Ms Lam's supervisor. He said that what is novel in her design is that their relatively large size means it doesn't seem to affect the healthy cells around the bacteria."
Honor
4 / 5 (1) Sep 14, 2016
im guessing it does a number on your gut microbes
ProBob
2.5 / 5 (2) Sep 15, 2016
If it could be introduced, and soon extracted, it may be able to limit this devistating effect to beneficial bacteria and other fragile membraines in the body. My first reaction on hearing of this becoming a drug therapy was that such material could stick in and clog up the brain endothelial cells, that is the blood-brain barrier that prevents most dangerous things from reaching the brain. If this became plugged, over even a brief treatment, the brain function would immediately suffer.
Nik_2213
not rated yet Sep 15, 2016
So it works like the 'auger' (sic) of a bacteriophage, which opens membrane for infection ?

That would make it very, very specific.
I hope...
electronism
not rated yet Sep 16, 2016
However it works, it might just be the answer!
roedy_green
1 / 5 (1) Sep 19, 2016
Body cells are resistant to the stars, even though these do not occur in nature, correct? That suggests to me that developing resistance should be fairly easy. Presumably, plants are immune too. Even if the time to develop resistance is double that of a typical antibiotic, it means even this new tool will have limited use.
Urgelt
1 / 5 (1) Sep 19, 2016
Roedy wrote, "Body cells are resistant to the stars, even though these do not occur in nature, correct? That suggests to me that developing resistance should be fairly easy."

Effects in humans haven't been studied. That's the first point to grasp. We don't know if human cells - which are much larger than nearly all bacterial cells - or if noncellular structures will be damaged by peptide stars.

Just as problematic, there is no specificity here. The peptide stars have no mechanism for sorting out which bacteria are pathogenic and which are symbiotic.

We have no information about how the body will process the peptide stars, either. Will the stars be broken down? What's the half-life? Will intact stars end up in the environment, and if so, what effects will that produce?

It's just basic research. And it doesn't seem to be far enough along to give us the sense that commercially-viable drugs could be based on this research.

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