Overlooked antibiotic re-enlisted in fight against drug-resistant superbugs
Overprescription and use of antibiotics is leading us down a terrifying path, towards a world where our best drugs simply don't work and even the most basic of medical procedures becomes deadly again. To prevent this future, Australian scientists have looked to the past, digging up a long forgotten antibiotic candidate and finding that it's effective against some of the most dangerous "superbugs."
The state of medicine is not looking great: a recent UK government report concluded that antibiotic-resistant bacteria could be responsible for up to 10 million deaths per year by 2050, and the cracks are already beginning to show. A class of drug called carbapenems are usually only used to fight infections that are immune to other drugs, and bacteria are becoming increasingly resistant to these too. Some are now developing resistance to colistin, an effective antibiotic that's not often administered because it's toxic to the kidneys.
"Gram-negative bacteria are harder to kill as disease organisms, because they have an extra membrane to penetrate that is often hidden by a capsule or slime layer which acts to camouflage them from drugs and our immune system," says Matt Cooper, director of the Centre for Superbug Solutions at the University of Queensland Institute for Molecular Bioscience. "The emergence of resistance to meropenem, and now colistin, the antibiotic of last resort, means multi-drug and extensively drug-resistant bacteria are now a reality confronting clinicians."
To try to turn the tides, researchers around the world are focused on developing brand new antibiotics and other high-tech weapons, as well as scouring the archives for old ones that might be able to rejoin the fight. And it's in that last category that scientists from the University of Queensland and Monash University have found a glimmer of hope, in the form of a class of drug called octapeptins.
"Octapeptins were discovered in the late 1970s but were not selected for development at the time, as there was an abundance of new antibiotics with thousands of people working in antibiotic research and development," says Cooper. "Given the very few researchers left in this field now, and the sparse pipeline for new antibiotics, we've used modern drug discovery procedures to re-evaluate its effectiveness against superbugs."
After identifying octapeptins as candidates, the researchers synthesized antibiotics from them, then boosted their effectiveness against resistant gram-negative bacteria. In their early pre-clinical tests in animal models, the scientists found that octapeptin was a better antimicrobial agent than colistin, and as a bonus, it doesn't seem to be as toxic to a patient's kidneys.
The researchers say the study could help develop new types of antibiotics, to stave off a return to "the dark ages of medicine" that superbugs could bring about if left unchecked.
The research was published in the journal Cell Chemical Biology.
Source: University of Queensland