TV presenter Sophie Morgan sits on a sofa with Professor Simon Gaisford

Everything You Need to Know About Antibiotics and the Gut Microbiome

Antibiotics, what do you know about them? Do you know how you should you be taking them? Or how to support your gut microbiome while on them? TV Presenter Sophie Morgan is on a mission to find out all there is to know. Which is why she met with Professor Simon Gaisford, Head of Pharmaceutics at UCL School of Pharmacy, to learn more about the relationship between antibiotics and the gut. 

On top of that, we asked Dr Sarah Jarvis to share the science behind antibiotics and some helpful things you can do to support your gut microbiome while taking them. Over to Dr Sarah Jarvis... 

Antibiotics, where did it all begin? 

It’s almost 100 years since the British scientist Alexander Fleming discovered the first antibiotic by accident. He coughed onto a Petri dish (used to grown colonies of bacteria) while he was working and left the dish by an open window.  

A few days later, all sorts of colonies of bacteria had grown on the dish, except in certain areas. He identified a ‘mould juice’ which could kill a range of bacteria responsible for pneumonia, meningitis and scarlet fever. He named the juice penicillin, and the world’s fight against bacteria was changed forever.  

Antibiotics, where did it all go wrong? 

For decades, doctors assumed that the supply of antibiotics would last forever. Even if the likelihood was that an infection was caused by a virus (where antibiotics would be useless), they wrote prescriptions ‘just in case’.  

But resistance of bacteria to penicillin had already been seen as early as 1942, and it continued apace. Every time bacteria multiply (sometimes as often as every 20 minutes) they can produce changes in their DNA (genetic material) called mutations. If a mutation helps them avoid being killed by an antibiotic, they will survive to multiply. If the other bacteria around them aren’t resistant and are killed off, they won’t have to compete with them for food and can multiply even more effectively. What’s more, bacteria can swap bits of DNA coding for resistance with other bacteria, allowing resistance to become more widespread.  

And new antibiotics are very few and far between. In fact, it’s over 35 years since we saw the development of a new antibiotic class (i.e. a completely new medicine that doesn’t work in a similar way to existing antibiotics). 

The consequence of ever-increasing antibiotic resistance and a lack of new options is clear. By 2019, The World Health Organisation was highlighting antimicrobial resistance as one of the top ten global public health threats facing humanity. 

Can antibiotics do me more harm than good? 

Antibiotic resistance isn’t just a problem for whole populations: there’s a risk of resistance to individual patients each time they take a course of antibiotics. A single course antibiotic could more than double your chance of your next infection being resistant to antibiotics, if you need more in the next 2 months. It’s even greater for children – in the 3 months after a course of antibiotics, any bacterial infection they get is 12 times more likely to be resistant. 

What would happen if we had no antibiotics? 

On the other side of the coin, there are many situations where you do need antibiotics. For severe infections like sepsis or pneumonia, they’re lifesaving: even for non-life-threatening infections, they can reduce suffering enormously.  

It’s estimated that if we had no access to antibiotics or anti-fungal medicines, up to 10 million more people a year would die worldwide. Routine surgery would become almost a thing of the past, because the risks of lethal infection would be so great. Medicines to damp down your immune system – which have revolutionised the lives of people with rheumatoid arthritis, lupus and a host of other conditions – would become far more dangerous to take.  

The good stuff – the gut microbiome 

As well as understanding more about the impact of resistance of harmful bacteria, the last couple of decades have seen an explosion of understanding about the gut microbiome. Far from being harmful, the 100 trillion micro-organisms (bacteria, fungi and viruses) that live in your gut play a vital role in: 

  • Preventing harmful bacteria from attaching to the gut wall and gaining a foothold. 
  • Producing vitamins essential for healthy bodily function (including vitamin K and several B vitamins). 
  • Playing a key part in the development of your immune system and how it matures. 
  • Helping to keep the junctions between cells lining the gut wall tightly locked together, thought to help reduce the risk of metabolic conditions such as type 2 diabetes. 

An imbalance of gut bacteria is called dysbiosis. This imbalance has been strongly linked to gut conditions – including irritable bowel syndrome (IBS) and possibly in the inflammatory bowel diseases, Crohn's disease and ulcerative colitis. 

But there’s even more. Dysbiosis is now thought to play a role in a host of conditions not limited to the gut – including obesity, raised cholesterol and possibly even depression. And because antibiotics don’t just kill the ‘bad guys’, they can have a major impact on your microbiome, encouraging dysbiosis. 

When do I need antibiotics? 

Your doctor will weigh up all the pros and cons of giving antibiotics if you have a possible viral infection. The vast majority of coughs, colds, sore throats etc are caused by viruses – so antibiotics won’t help at all and could cause harm.  

If the infection is minor, there’s a good chance your own immune system would fight it off just as quickly without antibiotics, even if it is bacterial. The exception is if you have an underlying health condition (including chronic lung, heart, kidney, liver or nervous system disease) which puts you at higher risk of serious complications. Here your doctor may step in earlier with antibiotics because the risk-benefit ratio is changed. 

How can I protect my gut if I need to take antibiotics? 

If you do need antibiotics, there are ways you can reduce the risk of them playing havoc with your system: 

  1. Eat a rainbow. The wider the variety of fruit, vegetables, nuts, seeds and pulses you eat, the more diverse your microbiome will be. This diversity gives it a better chance of having healthy bacteria which won’t be affected by the antibiotic. 
  2. Feed your good bacteria. Prebiotic foods contain ingredients such as inulin, which help your good bacteria thrive. Garlic, onions, apples, bananas, oats, beans, whole grains and Jerusalem artichokes are all good sources. 
  3. Top up the good stuff. Fermented foods – live yoghurt, sauerkraut, kombucha, kimchi, miso and kefir contain healthy bacteria which can tip the balance in your gut in favour of a healthy balanced microbiome. 
  4. Take a probiotic supplement with your antibiotic. A review of 29 studies looked at the impact of taking probiotics alongside antibiotics on the diversity and make-up of the gut microbiome. It showed that overall, probiotics reduce the impact of antibiotics on the microbiome.  

Dr Sarah Jarvis has acted as a medical advisor for Symprove. 


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