Drug-resistant "superbugs" represent one of the gravest threats in the history of medicine, leading experts warn.
Routine operations could become deadly "in the very near future" as bacteria evolve to resist the drugs we use to combat them.
This process could erase a century of medical advances, say British government doctors in a special editorial in The Lancet health journal.
Although the looming threat of antibiotic, or anti-microbial, resistance has been known about for years, the new warning reflects growing concern that Britain's NHS and other national health systems, already under pressure from ageing populations, will struggle to cope with the rising cost of caring for people in the "post-antibiotic era".
In a stark reflection of the seriousness of the threat, England's deputy chief medical officer, Professor John Watson, said: "I am concerned that in 20 years, if I go into hospital for a hip replacement, I could get an infection leading to major complications and possible death, simply because antibiotics no longer work as they do now."
Writing in The Lancet, experts, including England's chief medical officer, Dame Sally Davies, warn that death rates from bacterial infections "might return to those of the early 20th century".
They write: "Rarely has modern medicine faced such a grave threat. Without antibiotics, treatments from minor surgery to major transplants could become impossible, and healthcare costs are likely to spiral as we resort to newer, more expensive antibiotics and sustain longer hospital admissions."
Strategies to combat the rise in resistance include cutting the amount of antibiotics prescribed, improving hospital hygiene and incentivising the pharmaceutical industry to work on antibiotic alternatives.
But a leading GP told the Independent on Sunday the time had come for the public to take responsibility. "The change needs to come in patient expectation. We need public education: that not every ill needs a pill," said Dr Peter Swinyard, chairman of the Family Doctor Association.