Julien-images-videos-93/Shutterstock.comBacteria that are resistant to antibiotics are linked to millions of deaths a year – a number set to grow dramatically. From hospital wards to farms, resistance is being driven by how, and how often, we use antibiotics. Dr Sam Willcocks, director of the Antimicrobial Innovations Centre at Brunel University London, answers key questions about the issue, and points to some simple solutions.What are superbugs and where are you likely to encounter them?“Superbug” is the term used for bacteria that have become resistant to multiple antibiotics at once, and there are now many such bacteria found worldwide.To help focus research and public health efforts, the World Health Organization keeps a list of the drug-resistant bacteria it finds most concerning. These include several species resistant to carbapenems – often considered “antibiotics of last resort” – as well as MRSA (a well-known resistant form of the bacteria that causes staph infections) and multidrug-resistant tuberculosis. Many of these so-called “priority pathogens” are associated with hospital-acquired infections, where sick patients, invasive procedures and heavy antibiotic use all make it easier for resistance to take hold and spread. Others, such as drug-resistant tuberculosis, are widespread around the world – and not just in hospitals.How many people are dying from these infections?In 2024, a major study in the medical journal, The Lancet, researchers looked at 30 years of data on drug-resistant infections worldwide. They found that around 4.7 million deaths a year are linked to bacteria that have become resistant to the antibiotics we normally use to kill them. If nothing changes, the researchers predict superbug-associated deaths could rise to more than 8 million a year by 2050.Is antibiotic drug development an unwinnable arms race?Yes, but we can make it as difficult as possible. It is certainly true that bacteria are highly adept at evolving resistance to new antibiotics, especially if they are similar to compounds they have already seen before. This is why research scientists are putting their efforts into finding new classes of antibiotics, or using combinations of drugs with unique mechanisms of action. But new drugs alone won’t solve the problem. Other approaches include disabling the mechanisms that bacteria use to resist antibiotics; cutting back on antibiotic use when it isn’t truly needed; exploring alternatives to antibiotics, such as viruses that kill bacteria (called phages); and developing treatments that boost the immune system. Just as important is stopping infections happening in the first place, through vaccines, clean water and better hygiene.How bad could the situation get?The famous warning that, if we run out of effective antibiotics, one day you could die from a scratch is perhaps a little dramatic, but it captures a real concern. Most healthy people can fight off infection of minor cuts and scrapes without antibiotics, and that is unlikely to change. The greater threat is to the growing number of people who depend on antibiotics to make modern medicine safe: older adults, people with diabetes, cancer or weakened immune systems, women during childbirth, and people having surgery all face a higher risk of serious infection. Some of the most dangerous resistant bacteria are found in hospitals, but resistance itself isn’t confined there – it spreads between animals, people and the environment. That’s why the problem is increasingly tackled through a “One Health” approach, which treats human, animal and environmental health as interconnected. Most people won’t die from a scratch, but some might if there are no effective antibiotics. FotoDuets/Shutterstock.com Wouldn’t bacteria evolve resistance anyway, even in the absence of effective antibiotics?Yes, bacteria can evolve resistance even in the absence of human antibiotic use. Antibiotics are a modern discovery, not a modern invention. Microbes have been waging chemical warfare against one another for millions of years, producing antimicrobial compounds and evolving ways to evade them long before penicillin was discovered. The problem is one of scale. Human use of antibiotics – in medicine, farming and industry – has exposed huge numbers of bacteria to these drugs, far more than would ever happen in nature. That gives resistance more opportunities to emerge. And once it does, the genes responsible can spread quickly from one bacterium to another, so resistance can stick around and keep circulating long after the antibiotic that caused it has stopped being used.Do doctors still have many antibiotics to choose from?Doctors have dozens of antibiotics to choose from, grouped into about 20 families that work in five or six different ways. These include well-known types such as penicillins, tetracyclines and fluoroquinolones. Whether a particular drug works isn’t fixed, it depends on which bacteria are causing the infection and whether that specific strain has developed resistance to it.Very few antibiotics have become completely useless, but resistance is now widespread to some important drugs, including penicillins and carbapenems, which doctors often rely on when other options fail. The real danger is bacteria that resist multiple antibiotics at once, leaving doctors with few or no good options left. These infections are much harder to treat, sometimes requiring older drugs that are more toxic, more expensive or simply less likely to work.Where are antibiotics most overused?There’s no single culprit behind antibiotic overuse – human medicine, farming and the contamination of the wider environment all share the blame.In farming, huge quantities of antibiotics are given to healthy animals, often to help them grow faster or to prevent disease in crowded conditions. Antibiotics also leak into soil and rivers from industrial waste. In primary-care medicine, 20-30% of antibiotic prescriptions may be unnecessary or wrongly used, often because doctors have to decide quickly, without access to diagnostic tests that would tell them which antibiotics are most likely to be effective, or if they are even needed at all.And beneath all this are deeper problems: poverty, poor sanitation, limited access to healthcare, counterfeit medicines and weak health systems. That’s why antibiotic resistance isn’t just a medical problem; it’s a social, economic and environmental one too.How much antibiotic use is ‘too much’? Is there a threshold of use?There is no universal threshold beyond which antibiotic use suddenly becomes “too much”, but doctors do follow guidelines and scientists work out which doses work best. Problems can arise when bacteria are exposed to a dose too weak to kill them, since this gives resistant bacteria a chance to survive and multiply.But using too much is a problem too. It can cause more side-effects, and it exposes more bacteria in the body to the drug, giving resistance more chances to develop. Sometimes, antibiotics shouldn’t be used at all – for colds and flu, say, which are caused by viruses and don’t respond to antibiotics. That’s why modern guidelines focus on giving the right antibiotic at the right dose for the shortest time needed to work.Can we have one antibiotic to kill all harmful bacteria?Many antibiotics are already what are called “broad-spectrum” – they can kill many types of bacteria at once, rather than just one. This is useful when a doctor doesn’t yet know exactly what’s causing an infection and needs to start treatment straight away.But broad-spectrum antibiotics come with a catch. As well as killing the bacteria making you ill, they may also wipe out harmless bacteria, such as those living in your gut. The more bacteria are exposed to a drug, the more chances resistance has to develop. Because of this, scientists are now trying to develop more targeted antibiotics: ones that go after specific harmful bacteria while leaving the helpful ones alone, which should also help slow down resistance.What is the best way to beat antibiotic resistance? Does the answer lie in AI?There is no single fix for antibiotic resistance. In fact, some of the best ways to tackle the problem don’t involve creating new antibiotics at all. Preventing infections, increasing vaccination, using faster tests to identify infections, improving hygiene, making sure antibiotics are only used when they are really needed and cutting unnecessary use in both healthcare and farming can all make a big difference.Artificial intelligence is already helping. It is speeding up the search for new antibiotics, helping scientists find promising new drugs, improving tests that identify infections, and tracking the spread of antibiotic resistance. But AI is not a panacea. We still need to focus on the basics: preventing infections and using antibiotics responsibly.Sam Willcocks receives funding from UK Research and Innovation (UKRI).