It’s hard to imagine what life was like before the discovery of antibiotics, when common infections were life-threatening, but we could get the chance to find out if bacteria continue to evolve resistance to them.
Bacteria are simple microorganisms, which are vulnerable to antibiotic drugs that attack specific functions or growth processes in their cells (this is in contrast to viruses, which are basically just packets of genetic material that aren’t technically alive, and so don’t have chemical processes for the antibiotics to attack).
In a given sample of bacteria, some will have a genetic mutation that makes them resistant to a particular antibiotic. These mutations may be a change to the mechanism that the antibiotic targets, or it may introduce a means of exporting or degrading the antibiotic itself.
Because the bacteria with this resistant trait are more likely to survive in the presence of the antibiotic, they out-compete their non-resistant brethren and so come to dominate the population through natural selection. Or if they’re so inclined, they can also share their mutated genes with other bacteria through a process called conjugation – basically sex for single cells.
Either way, it’s an example of evolution in action. Creationists may object, usually by claiming these aren’t really beneficial mutations, because changes to the antibiotic-vulnerable processes often come at a cost to their efficiency. But after several generations they adapt ways around it and regain their efficiency, so yes it really is Darwin’s evolution through natural selection.
Similarly, it’s important to remember that the mutations are random: the antibiotics aren’t actually causing them to appear. In fact, the mutations can usually be found to a small extent in the bacterial populations before the antibiotics arrive. But once they do arrive, they change the conditions of the environment and give the resistant bacteria an advantage.
This all means that the more we use antibiotics, the more resistant bacteria will get the upper hand. And that means that we’ll increasingly see infections our drugs can’t fight, like the potentially deadly multi-resistant Staphylococcus aureus (MRSA), or golden staph.
Or to take another example that’s had a lot of attention lately, the sexually-transmitted infection gonorrhoea has started appearing in strains resistant to all antibiotics. Untreated, gonorrhoea can lead to many complications, including infertility, stillbirths and blindness in babies born to infected women.
The World Health Organisation (WHO) recently released an action plan urging a global response to this threat. But what can you do to help fight gonorrhoea and other resistant bacteria?
Well, in Australia the National Prescribing Service (NPS) is currently running a campaign to encourage people to take 3 simple actions:
- Don’t expect to take antibiotics for colds and flu, because they are caused by viruses, not bacteria.
- If you are prescribed antibiotics, take them as directed, including the right dose and for as long as your health professional tells you to, even if you feel better (otherwise you let the bacteria live longer to build up resistance).
- Take simple steps like washing your hands, to avoid infections and prevent them from spreading.
Go to the NPS website at www.nps.org.au to find out more, and to take a pledge to help fight resistance.