Forget the cataclysmic weather event, the nuclear apocalypse, the alien takeover, or the zombie invasion – what researchers are increasingly coming to believe will bring down the human race is microscopic: bacteria. The over-prescription and over-use of antibiotics in recent decades has led bacteria to develop tolerances to the drugs that are currently on the market. And, as bacteria increasingly evolves its resistance to antibiotics, we could be cast back into the dark ages of medicine, scientists say. Antibiotics are our last line of defence in many cases where they stop the spread of infection. Without them, we are all in big trouble. Reports suggest that if left unchecked, “superbugs” could be responsible for up to 10 million deaths annually by 2050. To put that number into perspective, consider that there are currently 56 million people in South Africa, or 53 million in England. So we are talking about roughly 20 % of those populations each year.
The dilemma gets even more dismal because not only is bacteria increasingly becoming resistant to antibiotics, some bugs have managed to turn the drugs into a food source. Yes, the bugs are eating our antibiotics. The very thing that is meant to end them is instead sustaining them.
Research being undertaken by the Washington University School of Medicine in St Louis is looking into how bacteria is able to do this. According to Gautam Dantas, senior author of the study, when it was first discovered 10 years ago that bacteria could eat antibiotics, everyone was shocked by it. However, it is now beginning to make sense, he says. “It’s just carbon, and wherever there’s carbon, somebody will figure out how to eat it. Now that we understand how these bacteria do it, we can start thinking of ways to use this ability to get rid of antibiotics where they are causing harm.”
Luckily, we have not lost the battle against superbugs yet. Bacteria have strong cell walls that protect it against drugs, viruses and other dangers, making it pretty tough to kill. Except that researchers at Harvard Medical School think they have found an Achilles heel, a structural weakness that is seemingly built into a range of bacterial species.
The Harvard study focused on a protein called Roda, which builds the protective cell walls of bacteria out of sugar molecules and amino acids. Roda belongs to a family of proteins that is common to almost all bacteria, making it the ideal target for a broadspectrum antibiotic. Further study revealed a vulnerable-looking cavity on the outer surface of the protein which, when altered, caused the protein to malfunction, leading the bacteria to first bloat and then burst, ultimately killing it. According to scientists working on the study, this suggests that a drug designed to prompt the same reaction would be an effective antibiotic in the future.
While they work to find solutions to the looming superbug crisis, scientists have also looked to nature for alternatives to antibiotics. Potential has been found thus far in fairly innocuous foods like berries, honey, maple syrup, and fungi, but also stranger sources such as frog skin, rattlesnake venom and platypus milk.
A new study involving researchers from Australia’s University of Queensland and Spain’s Pompeu Fabra University is testing a new antibiotic contender, the peptide Crotalicidin (Ctn), found in the venom gland of South American rattlesnakes. Prior research revealed that this particular peptide possesses antimicrobial properties and was not only highly effective at killing bacteria, but also less toxic to healthy cells.
Sónia Troeira Henriques, co-author of the study, has called this “an example of taking what nature has given us and trying to understand how it works, so we can modify it to be more potent, more stable or more drug-like, to use as an alternative to what we have in our pharmacies now”.
Platypus milk is also under the microscope – quite literally – as a team of Australian researchers discovered several years ago that it contains innovative antimicrobial properties likely due to a unique protein found in the milk. Platypuses, part of the monotreme family, are fascinating creatures – they lay eggs like reptiles but feed their babies milk, like mammals. Except that they have no teats, so milk is expressed through pores on the mother’s belly. The milk pools in grooves from which the babies then lap it up. It is this process which scientists believe exposes the milk to bacteria in the environment.
This unusual protein – only found in the milk of monotremes – has since been successfully replicated in a lab, where it was found to have a novel ringlet-like formation, leading it to be nicknamed the “Shirley Temple” protein. Scientists working on the study have said that the discovery increases the scope of knowledge of protein structures in general, and will go on to inform other drug discovery work currently being done.
There is no doubt that we are in trouble. Our over-dependence on and over-use of antibiotics having created a sombre and sobering situation which, if not given immediate and adequate attention, may well be the catastrophic event that takes man out of the equation entirely.