Telling GPs when they give out too many antibiotics could cut the number of unnecessary prescriptions, research suggests.
Sending GPs a letter about their habits cut antibiotic prescribing by an average of 3.3% over six months, a new study involving more than 1,500 GP practices in England found.
England's chief medical officer Professor Dame Sally Davies, who was involved in the study, has described the issue of antibiotic resistance as a "ticking timebomb".
Experts have warned that some infections will become untreatable in the future as bacteria become more and more resistant to antibiotics.
Inappropriate use of antibiotics is one of the reasons why bacteria are growing in resistance. Another issue is when people fail to take a whole course of antibiotics, while some experts say the widespread use of antibiotics in animals means resistant strains of bacteria are being transmitted to humans through food.
In the new study, published in The Lancet medical journal, experts found that sending letters to GPs with high prescribing rates resulted in over 73,000 fewer prescriptions and direct savings of more than £92,000 in prescription costs.
During a six-month period in winter 2014/15, letters were sent to practices across England who had antibiotic prescribing rates in the top 20% for their area.
In one half of the trial, the letter, signed by Dame Sally, said "80% of practices in their local area prescribe fewer antibiotics per head than yours" and gave simple tips on reducing prescribing.
The second half tested the effects of a poster and leaflet campaign in GP practices telling members of the public why antibiotics were not always necessary.
The results showed that GP letters were effective in cutting prescribing rates, while there was little effect from the poster campaign.
The trial was a collaboration between Dame Sally, Public Health England, the Department of Health, and the Behavioural Insights Team, which is independent of government but partly owned by the Cabinet Office.
The UK has a five-year aim of reducing antibiotic prescribing in GP practices by 4%.
Dame Sally said: "We know that drug-resistant infections are one of the biggest health threats we face.
"This innovative trial has shown effective and low-cost ways to reduce unnecessary prescribing of antibiotics, which is essential if we are to preserve these precious medicines and help to save modern medicine as we know it."
Lead author Michael Hallsworth, from the Behavioural Insights Team, said: "Giving tailored feedback to prescribers isn't complicated.
"We estimate that this simple intervention could reduce England's antibiotic prescribing by 0.85% overall, despite costing just 6p per prescription saved.
"This kind of feedback could also be provided for many other kinds of drugs."
Despite the push to cut antibiotic prescribing, there have been warnings that some patients are slipping through the net.
An NHS England report in January following the death of 12-month-old William Mead from sepsis said GPs were under "constant pressure" not to prescribe antibiotics, which could have saved his life.
Dr Maureen Baker, chairwoman of the Royal College of GPs, welcomed the study and said: "GPs can come under huge pressure from patients to prescribe antibiotics, even when we know they are not the best course of action. Our patients need to realise that this is dangerous for each and every one of us, not just 'other people'."
She added: "GPs already undertake regular prescribing reviews to see what they can do differently in the best interests of their patients. Reminder letters could be seen as an extension to this - or a prompt - but it's important that doctors who receive letters don't feel overly criticised as a result .
"There is nothing to say that doctors who prescribe the most antibiotics are doing so inappropriately; some doctors will prescribe more than others simply as a result of the demographics of their patients."
Dr Baker said it is "concerning" that there has been no new class of antibiotics produced in more than 25 years.
"We seriously need investment into research to develop new drugs that are effective at tackling existing and emerging diseases," she added.