There are 10 times as many bacteria living on and in your body than there are human cells that you could call your own. Some of these bacteria are your friends – they help you digest your food, even moisturize your skin. Others are not so friendly, but chances are you haven’t given much thought to them. If they ever get out of line, all you need do is take some pills and you’ll definitely be OK. Right? Wrong.

The age of antibiotics may be coming to a close, and one of humankind’s greatest adversaries could once again have the upper hand. In the EU, about 25,000 patients die every year from infection with bacteria that are resistant to all the drugs we have to fight them, while in the US some antibiotic-resistant infections cause more deaths than HIV/AIDS, Parkinson’s disease, emphysema, and homicide combined. Meanwhile, the R&D pipelines for new classes of antibiotics are running dry.

It’s not hard to imagine a world without antibiotics: just turn the clock back 80 odd years. When penicillin came on the market in the 1930s, it increased survival rates from pneumonia and blood infection from 10% to 90%. In a world without antibiotics, when you injure your knee playing sports you won’t have surgery, you will have to put up with a limp, or endure an amputation. Your parents or grandparents won’t go in for a hip replacement, they’ll be bedridden at home until they die. Your child or sibling who is born prematurely won’t have a chance, and suddenly tonsillitis in primary schools will become headline news, as a deadly bout sweeps through town in winter.

But that’s not all. Organ transplants, chemotherapy, plastic surgery or any surgery – the very miracles of modern medicine – all become impossible, or much more likely to fail or end in death. Infections which our existing arsenal can no longer cure are becoming common place.

The annual economic costs in terms of healthcare and lost productivity amount to billions of dollars. In light of such grave concerns it may seem trivial, but some foods would also become more expensive in a world without antibiotics. We rely on antibiotics to prevent epidemics in poultry and livestock that are raised in large-scale farming operations. The bottom line is that losing antibiotics means losing many things taken for granted in advanced economies, whether that’s a safe birth for mother and child, or a turkey dinner that more than the “1%” can afford.

Sadly, the so-called wonder drugs that were expected to forever “close the book on infectious disease” are by no means infallible in the face of enemies that seem far more talented at evolving than we are at innovating solutions in the lab. It’s an arms race we are losing and the scariest part is that our weapon of choice only makes our enemies stronger. Bacteria strong enough to survive our antibiotic defences are the bacteria that live to reproduce and share their abilities with others.

Mitigating this risk requires new weapons. The inevitability of antibiotic resistance calls for new research into innovative defences beyond traditional antibiotic therapies, such as nanotech and techniques that change bacterial behaviours. Our scientists need to be find ways of outwitting one of the wiliest enemies in nature if we are to stop this nightmarish vision of a world without antibiotics turning into reality.

This series of “What if” blog posts is inspired by the findings of the Global Risks 2012 report. The scenarios they depict are far-fetched, but ultimately plausible. Read the first post: What if a supervolcano erupted?. What if there was no more space in space? will follow later today.

Pictured: a patient in hospital in Xining, China. If we lost the use of antibiotics, even routine trips to hospital would become highly dangerous (Thomson Reuters).