An introduction to antimicrobial resistance

What is the difference between antibiotic and antimicrobial resistance?

Antibiotics are medicines used to prevent and treat bacterial infections. Antibiotic resistance occurs when bacteria change in response to the use of these medicines. Bacteria, not humans, become antibiotic resistant. These bacteria may then infect humans and are harder to treat than non-resistant bacteria.

Antimicrobial resistance is a broader term, encompassing resistance to drugs to treat infections caused by other microbes as well, such as parasites (e.g. malaria), viruses (e.g. HIV) and fungi (e.g. Candida).

Everything you ever wanted to know about the bugs and drugs that are shaping our world

Antibiotics are a hot topic. When these lifesaving drugs were first developed, back in the early 20th century, we sort of assumed everything was okay now – no more dying over grazed knees and paper cuts. But unfortunately, it looks like that isn’t the case.

We’ve used antibiotics so much that some bugs have now learnt how to resist virtually everything we have. So what can we do? Well, the good news is that there’s lots of great work taking place in this area, and everyone – from doctors, to politicians, to everyday people – can help.

So here’s the lowdown on antibiotic resistance: from the sources, to how it’s spread, to the solutions.

The source: what causes resistance?

In short: overuse. The more we use antibiotics, the more opportunities there are for bacteria to evolve resistance. And in the past, we’ve been quick to use these drugs when they weren’t strictly necessary.

Now there are other factors at play here; for instance, modern chemical pollution has also been found to exacerbate the problem of resistance. But overuse is by far and away the most powerful cause of antibiotic resistance. So how exactly does using too many antibiotics translate into resistance? 

Well, first off, it’s worth noting that antibiotic resistance has been around for a long time – long before we even knew antibiotics existed. In recent years, scientists have discovered antibiotic resistant genes dating back 30,000 years. It’s always been there, but the problem is that we’ve made it worse.

Antibiotics work by interfering with the processes that bacteria need to grow and survive; maybe they destroy the bacteria’s protective cell wall, or starve it of sustenance. But bacteria can sidestep these mechanisms in a number of ways.

They might change the structure or characteristics of the part of themselves that antibiotics target – this can prevent the drugs from detecting or reaching the bit of the bacteria they interact with. Or they might learn to develop enzymes that destroy the antibiotics altogether.

These resistance mechanisms are born out of a ‘survival of the fittest’ process, whereby bacteria that have protective characteristics are more likely to survive an antibiotic attack and pass those resistance genes on to their ‘children’.

And here’s the kicker: we’ve been using and misusing antibiotics for so long now, there’s a lot of bacteria out there that have evolved or acquired the resistance mechanisms they need to survive.

The spread: how does resistance circulate?

So that’s resistance on the molecular level, but how do drug resistant bacteria spread on a human scale? The answer is…well, it’s complicated. Human and animal medicine play an important role, as does air travel, but there’s a number of different ways in which drug resistant bacteria manage to make their way around.

So let’s start with hospitals. Unfortunately, because of all the sick people, healthcare settings are home to some of the most aggressive superbugs. Some common hospital acquired infections, like MRSA, have developed resistance to multiple antibiotics, making them really difficult to treat. So you’re more likely to acquire antibiotic resistant bugs in hospital than in everyday life; but what’s more, because people come and go from hospital all the time, these bugs have plenty of opportunities to spread.

But people aren’t the only ones spreading infections. In Europe, Antibiotics have been used as preventative medicine in agriculture since 1953. The idea is that by dosing the animals with antibiotics blended into their food, they’re less likely to become sick; the problem is that the antibiotics used for this practice are the same ones we use to treat humans. That means that bacteria have more opportunities to evolve resistance, and those resistant bacteria could get passed on to humans.

To make matters worse, resistant bacteria circulate in the environment and are sometimes washed into rivers and seas as wastewater from sewage.  These resistance bacteria can then transfer to animals and humans that pass by. High levels of resistant bacteria have been found in some of Britain’s waterways, and studies show that surfers and other people who spend a lot of time in the water are at a higher risk of ingesting strains of resistant E.coli.

And then there’s the nature of modern life. Once somebody has acquired a drug-resistant infection, ease of travel makes it easier than ever to spread disease. People infected with these bacteria could come into contact with multiple communities, sometimes transporting the bugs all over the world, before they can be treated.

So there are a number of factors at play when it comes to the spread of resistance, and no one source can be pinpointed as the sole culprit. That means addressing this issue will require action on all fronts – from the hospital bed to the farmyard.

The solutions: what can we do?

So that’s what we’re dealing with here; but it’s not all doom and gloom. There’s plenty that we can do to combat resistance, both on an individual and a global scale.

We know that antibiotic misuse is at the root of the problem, and that’s something that we can all work to improve. We should absolutely take antibiotics when they’re necessary; but we should only take them when they’re necessary.

These drugs only work on bacterial infections, not viruses like colds and flu. If we do take antibiotics for a virus, it doesn’t help anyone, except the bugs. Also, vaccinations can prevent some infections from occurring in the first place. No infection; no need for antibiotics. Finally, it’s really important to follow doctor’s advice with these things – don’t stop taking antibiotics or give them to somebody else – the rules are there for a reason!

So that’s how the general public can help, but what about the bigger picture? Research is at the very core of efforts to combat resistance. Part of the problem is that we’ve been using the same classes of antibiotics for decades, giving bugs ample time to learn how to fight back.

If we can develop new classes of antibiotics, or innovative ways of sidestepping the problem altogether, then we’ll be much better equipped when it comes to beating the bugs.

Towards a safer world

Combatting resistance isn’t easy, and it’ll take the hard work of scientists, policymakers, clinicians and individuals to keep the bugs at bay; but we’re not powerless.

When it comes to antibiotic resistance, knowledge is power. The more we understand this problem, the better equipped we are to fix it; and together, we can make a difference.