Antibiotic-resistant bacteria with the potential to cause untreatable infections pose "a catastrophic threat" to the population, the British chief medical officer warns in a report calling for urgent action worldwide.
If tough measures are not taken to restrict the use of antibiotics and no new ones are discovered, said Dame Sally Davies, "we will find ourselves in a health system not dissimilar to the early 19th century at some point".
While antibiotics are failing, new bacterial diseases are on the rise. Although the "superbugs" MRSA and C difficile have been reduced to low numbers in hospitals, there has been an alarming increase in other types of bacteria including new strains of E coli and Klebsiella, which causes pneumonia.
These so-called "gram negative" bacteria, which are found in the gut instead of on the skin, are highly dangerous to older and frailer people and few antibiotics remain effective against drug-resistant strains.
As many as 5,000 patients die each year in the UK of gram negative sepsis - where the bacterium gets into the bloodstream - and in half the cases the bacterium is resistant to drugs.
"Antimicrobial resistance poses a catastrophic threat," said Davies. "That's why governments and organisations across the world, including the World Health Organisation and G8, need to take this seriously."
There has been an 85% reduction in MRSA (methicillin-resistant Staphylococcus aureus), which has meant that many large, acute hospitals have no more than two or three cases a year. But there are now 50 to 100 cases of gram-negative bacteria infection for every MRSA case, according to Professor Mike Sharland of St George's hospital in London, an adviser to the Department of Health on the use of antimicrobials (antibiotics and antivirals) in children.
"This is your own gut bugs turning on you. Between 10% and 20% are resistant to drugs. We do not yet know why they are on the rise, although some hospital procedures, such as the use of catheters, may be implicated. Many are in the very young or older population," he said.
"There is a lot of work going on through Public Health England and the Department of Health to try to work out why it has suddenly risen." In the second volume of her annual report, Davies calls for politicians to treat the threat of the new bugs and the failing antibiotics as seriously as they did MRSA.