The World Health Organization published a new classification of antibiotics on Tuesday that aims to fight drug resistance, with penicillin-type drugs recommended as the first line of defense and others only for use when absolutely necessary.
The new "essential medicines list" includes 39 antibiotics for 21 common syndromes, categorized into three groups: "Access", "Watch" and "Reserve".
Drugs on the "Access" list have lower resistance potential and include the widely-used amoxicillin.
The "Watch" list includes ciprofloxacin, which is commonly prescribed for cystitis and strep throat but "not that effective", WHO Assistant Director-General for Health Systems and Innovation Marie-Paule Kieny told reporters.
Its use should be "dramatically reduced", the WHO said.
"We think that the political will is there but this needs to be followed by strong policies," Kieny said.
In the "Reserve" category antibiotics such as colistin should be seen as a last resort. That prompts questions about how producers of such antibiotics could make money, said Suzanne Hill, WHO's Director of Essential Medicines and Health Products.
"What we need to do is stop paying for antibiotics based on how many times they are prescribed, to discourage use. We don't want colistin used very frequently. In fact we don't want it used at all," Hill said.
"What we need to do as a global community is work out how we pay the company not to market colistin and not to promote it and to keep it in reserve."
The WHO classification takes into account the use of antibiotics for animal health use, and was developed together with the U.N. Food and Agriculture Organisation and the World Organisation for Animal Health.
Other changes to the list included the addition of two oral cancer treatments, a new pill for hepatitis C that combines two medicines, a more effective treatment for HIV, and new paediatric formulations of medicines for tuberculosis.
But the WHO also said Roche's well-known flu drug oseltamivir, marketed as Tamiflu, may be removed from the list unless new information supports its use in seasonal and pandemic influenza outbreaks.
"There is an updated data set compared to when the committee evaluated this product last, and what that suggests is that the size of the effect of oseltamivir in the context of pandemic influenza is less than previously thought," Hill said.
But oseltamivir was the only listed antiviral, and was still useful for pregnant women and patients with complications, so the drug should be restricted to the most critical patients, she added.