The rise of superbugs, stoked by misuse of antibiotics and shoddy hospital hygiene, is enabling long-treatable diseases to once again become killers, the World Health Organisation warns.

In a hard-hitting study of antimicrobial resistance - when bacteria adapt so existing drugs no longer stop them - the UN health agency says the issue is a global emergency and urges all players to wake up.

"Without urgent, co-ordinated action by many stakeholders, the world is headed for a post-antibiotic era, in which common infections and minor injuries which have been treatable for decades can once again kill," warned Keiji Fukuda, the WHO's assistant director-general for health security.

Antibiotics had enabled people to live longer, healthier lives and benefit from medical advances, but this was now under threat, Fukuda said in a statement.

"Unless we take significant actions to improve efforts to prevent infections and also change how we produce, prescribe and use antibiotics, the world will lose more and more of these global public health goods and the implications will be devastating," he said.

The WHO combed through data from 114 countries in the study.

It focused on seven different bacteria responsible for common, serious diseases such as sepsis, diarrhoea, pneumonia, urinary tract infections and gonorrhoea.

Even so-called "last resort" antibiotics are losing their ability to fight such bacteria. Half of patients show resistance in some countries, the report says.

Among the key findings were the global spread of resistance to carbapenem antibiotics, the last-resort treatment for life-threatening infections caused by the common intestinal bacteria Klebsiella pneumoniae.

Known as K. pneumoniae, it is a major cause of hospital-acquired infections such as pneumonia and sepsis, often hitting newborns and intensive-care patients.

Resistance to fluoroquinolones, one of the most widely used antibacterial medicines for the treatment of urinary tract infections caused by E. coli, is also widespread.

Resistance was virtually zero when the drugs were introduced in the 1980s, but now hits half of patients in many part of the world, the WHO said.

The problem is a particular concern in Africa, the Americas, South and Southeast Asia, and the Middle East.

Resistance to third-generation cephalosporins - the last resort for tackling gonorrhoea, which infects more than a million people every day - has been confirmed in Austria, Australia, Britain, Canada, France, Japan, Norway, South Africa, Slovenia and Sweden.

Antibiotic resistance also had a knock-on effect by causing people to be sick for longer and making them more likely to die, the WHO said.