Antibiotic Resistance – a modern-day cause?

Have you ever felt a bit unwell, maybe with a cough, and popped to the doctors to get some antibiotics? Fortunately, we live in a world where this is common practice, and we can be back to our normal selves within days. However, imagine a time before antibiotics. Imagine a time where people were seriously ill with the most simple of bacterial infections, and, scarily, you could be imagining a time not too far away!

It is an increasing worry in modern day medicine that more and more strains of bacteria are becoming resistant to antibiotics. The most famous, MRSA (multi-resistant Staphylococcus aureus), is in fact resistant to almost all antibiotics on the market, making it a very dangerous infection to have, even though it used to be fought off without the patient even developing many symptoms. So could we really be moving back into the dark ages?

What is resistance?

Antibiotic resistance is at the end of the day just down to a random mutation in the DNA of the bacteria, and mutation rates are only one in a million bacterium. However, when you think of the potential trillions of bacteria that live on your skin that makes for quite a large number of mutations! Although they’re entirely random, it just so happens that some of them end up giving the bacteria resistance to a type of antibiotic. Resistance comes in many forms. It can be a pump within the bacteria cell wall that just moves the antibiotic out as soon as it gets in. It can be enzymes produced to target and breakdown the antibiotic itself. It can even be the bacteria changing how it functions so that the antibiotic has nothing to bind to. Any kind of mechanism you can think of could be developed through these random mutations.

Antibiotics - image courtesy of Iqbal Osman, Flickr

Antibiotics – image courtesy of Iqbal Osman, Flickr

How does resistance spread?

Bacteria aren’t clever, they don’t know that they possess resistance until they come across antibiotic that they are resistant to. When this happens, that bacteria is going to have an advantage over all of the others, and it’s going to survive, and it’s going to clone itself to form more bacteria, and so the resistance spreads. This is one of the reasons that it is so important to finish a course of antibiotics, even if you’re already beginning to feel better, because those last few bacteria left will be the most resistant, and they will be the ones to thrive and multiply.

It has also been discovered that bacteria can, effectively, have sex. A bacterium with a certain aspect of DNA known as an ‘F plasmid’ – the male – can extend a long sex pilus into a bacterium without the plasmid – the female – and pass on certain information. Unfortunately, sometimes the information that can be passed on is that of the antibiotic resistance, and the accepting female can then incorporate that information into her DNA and also become resistant. This can even happen between certain strains of bacteria, not just within one species.

Bacteria - image courtesy of Umberto Salvagnin, Flickr

Bacteria – image courtesy of Umberto Salvagnin, Flickr

Can’t we just make more antibiotics?

Antibiotics are notoriously difficult to create. The best ones are actually extracted from bacteria found usually in soil. These bacteria are already resistant, and use the antibiotics to defend themselves against other strains of bacteria that might give competition for food or living space. By growing these bacteria in the labs and extracting the antibiotics, we can use them in medicine. However, 99% of bacteria cannot be grown in a lab, and unfortunately we have found just about all the antibiotics from that 1% that we can grow. And synthetic antibiotics are so difficult to create, that they take decades to be developed and even then often fail.

Is there any hope?!

Yes, there is hope! A new way of culturing some of that 99% has been discovered. This novel technique involves a device called the iChip, which allows the bacteria to be grown naturally in their own habitats in the soil whilst still being contained, using a semipermeable membrane to allow nutrients to flow through. This has opened up a whole new world of possibilities, and already a new antibiotic – teixobactin – has been discovered to be effective against many strains of bacteria, including MRSA, and so far no strain has developed resistance against it; the drug is currently going through clinical trials.

So, although it seems scary to think of all that resistance, scientists are constantly coming up with new ways to develop medicine. Thanks to this new technology, there is now huge potential for developing further antibiotics, and more techniques are being worked on every day.

Reference: Ling, L.L., Schneider, T., Peoples, A.J., Spoering, A.L., Engels, I., Conlon, B.P., Mueller, A., Schäberle, T.F., Hughes, D.E., Epstein, S., Jones, M., Lazarides, L., Steadman, V.A., Cohen, D.R., Felix, C.R., Fetterman, K.A., Millett, W.P., Nitti, A.G., Zullo, A.M., Chen, C. and Lewis, K. (2015) ‘A new antibiotic kills pathogens without detectable resistance’, Nature, 517(7535), pp. 455–459. doi: 10.1038/nature14098.

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