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10. Treating Infections with Antimicrobials

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Throughout the week we have been looking at the marvellous and amazing roles that microbes play in shaping our world and our lives. However, some microbes can cause human or animal infections. Just now, many scientists are working very hard to find new ways to treat the virus called Sars-CoV-2, a coronavirus that causes COVID-19.

“Antimicrobials” are substances that kill a microbe or stop it from replicating (making more copies of itself). Antimicrobials can be split into different classes depending on which type of microbe they target.

For example:

  • Antivirals target viruses
  • Antibiotics target bacteria
  • Antifungals target fungi
  • Antiparasitics target parasites

Antimicrobials are an important part of modern medicine. For example, without effective antibiotics many common surgeries and accidents could become life threatening. Did you know that Scottish biologist and doctor Sir Alexander Fleming was involved in the development of penicillin, an antibiotic that we still use today?

Watch this video to learn more about “The accident that led to penicillin”:

Our friends at the National Museum of Scotland have some amazing objects in this area, including samples of penicillin mould donated by Sir Alexander. Find our more by visiting.

You can also learn more about key dates in the history of antibiotics by downloading and reading

Activity: Antibiotic Timeline - Why don’t you make your own antibiotic timeline and share it with us? You could pick eight key events that you want to highlight.

Antimicrobial Resistance

Antimicrobials are amazing tools for treating many different infections. However, over time microbes can develop ways to resist the medicines, which means the antimicrobial will no longer work – this is called resistance. The resistance can happen naturally as microbes reproduce very quickly and change to allow them to grow in the presence of the medicine. Because antimicrobials are used a lot in medicine and agriculture this has made them change more quickly. Therefore, it is very important only to take antibiotics (and other medicines) when you are told to by a doctor and to follow the prescription guidance.

Making New Antimicrobials

There are two main routes that scientists use to develop new antimicrobial compounds.

One involves taking inspiration from nature. You found out on Wednesday that leaf-cutter ants carry microbes to help keep their fungal gardens clean. Many bacteria make antibiotics to fight off other microbes that live in the surrounding area. This means that they can keep food and other resources to themselves.

Bacteria that live in the soil are especially good at making antibiotics. In fact, the first antibiotic that was identified from a soil bacterium was tetracycline which was initially used in 1948. In the image below you can see bacteria that have been isolated from soil by pupils from Baldragon Academy, Dundee. In this sample the pupils found one bacterium that protected the surrounding area from invasion by the other microbes and formed a cleared halo around it - can you see it? Lots of scientists are looking for new antibiotics using bacteria from many different habitats.

There is even a chance to look for new antibiotics in places you choose (£):

At the University of Dundee, we are also specially placed to use another route to make new medicines.

Most new medicines are made by big companies. It’s a very expensive process, which needs skilled people and complex robots. They can only afford to research medicines they think will make a profit. In a university, we can research things that we think are important to society, whether they make money or not. Having a medicine-making company as part of a university means we can get the best of both worlds. We can research important medicines to help people without a lot of money at our Drug Discovery Unit. No one else in the world works the way we do, and we’re very proud of it.

Our team of biologists can take existing molecules and test them to see if they work against infection-causing microbes – and make sure they don’t hurt people. Our medicinal chemists can then change the shape of the molecule to try and improve it. They can add on atoms in different places, based on what they know about how the shapes work. Together, the teams run a cycle of design, make and test, design make and test.

So far, we’ve made two really exiting potential medicines to fight parasites. One fights malaria, a disease lots of people have heard of, and the other is for leishmaniasis. This horrible parasite is not as well known – in fact, it’s classed as a Neglected Tropical Disease by the World Health Organisation.

Some of our scientists have written a free book for young people where you can find out more about Leishmania - it’s called Kirsty’s Story.

Why don’t you take a look?

Activity: Download our Antimicrobial Word Search. Can you find all the words in this word search? Look closely.
Antimicrobial Word Search (PDF)
Antimicrobial Word Search (PDF) Answers (PDF)
Petri Dish
Petri Dish

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