The world is running out of antibiotics, global health leaders have warned.
The World Health Organisation (WHO) said that "antimicrobial resistance is a global health emergency".
Growing resistance to drugs that fight infections could "seriously jeopardise" progress made in modern medicine, the head of WHO said.
The remarks come after a new WHO report found a serious lack of new drugs in development to combat the growing threat of antibiotic resistance.
Health experts have previously warned that resistance to antimicrobial drugs could cause a bigger threat to mankind than cancer.
In recent years, there has been a UK drive to raise global awareness of the threat posed to modern medicine by antimicrobial resistance.
If antibiotics lose their effectiveness, then key medical procedures - including gut surgery, caesarean sections, joint replacements and chemotherapy - could become too dangerous to perform.
Around 700,000 people around the world die annually due to drug-resistant infections including drug-resistant tuberculosis (TB), HIV and malaria. If no action is taken, it has been estimated that drug-resistant infections will kill 10 million people a year by 2050.
The WHO previously drew up a list of antibiotic-resistant infections posing the greatest threat to health. It has now examined new drugs in the development pipeline.
The new WHO report found few potential treatment options for those antibiotic-resistant infections - including drug-resistant tuberculosis (TB) which kills around 250,000 people each year.
There is also a lack of treatment options for gram-negative pathogens, including Acinetobacter and Enterobacteriaceae, such as Klebsiella and E.coli - which can cause deadly infections and pose a particular threat in hospitals and nursing homes, WHO said.
Meanwhile there are very few oral antibiotics for infections caused by gram-negative pathogens in the pipeline, even though such drugs are essential for treating infections outside hospitals.
The authors of the report identified 51 new antibiotics and biologicals in clinical development. But the WHO said that only eight of these are deemed to be innovative treatments that will add value to the current antibiotic treatment arsenal.
Most drugs in development are modifications of existing antibiotics, which are "only short-term solutions", the authors said.
"The current clinical pipeline is still insufficient to mitigate the threat of antimicrobial resistance," they added.
The authors called for more investment in basic science, drug discovery and clinical development.
Dr Tedros Adhanom Ghebreyesus, director-general of WHO, said: "There is an urgent need for more investment in research and development for antibiotic-resistant infections including TB, otherwise we will be forced back to a time when people feared common infections and risked their lives from minor surgery."
Earlier this month the Government and the British research charity the Wellcome Trust joined Germany, Luxembourg, the Netherlands, South Africa, Switzerland to pledge more than EUR56 million to the Global Antibiotic Research and Development Partnership.
Ed Whiting, director of policy at the Wellcome Trust, added: "We've made good progress in getting this on the political agenda. But now, a year on from a major UN agreement, we must see concerted action - to reinvigorate the antibiotic pipeline, ensure responsible use of existing antibiotics, and address this threat across human, animal and environmental health."