A quarter of people wrongly believe antibiotics work on most coughs and colds, a British Health Protection Agency (HPA) survey has found.However antibiotics cannot treat viruses, which cause most respiratory tract infections.The HPA poll of 1,800 people in England also found one in 10 people keep leftover antibiotics - and many would self-medicate next time they got ill.A leading GP said antibiotics were not a \"cure all\".The HPA\'s Dr Cliodna McNulty said self-medicating was unsafe and could fuel drug resistance.Dr McNulty, head of primary care for the HPA, said \"The majority of people can treat themselves at home using over-the-counter medicines to relieve symptoms.\" Of those polled, 500 had been prescribed antibiotics in the previous year, with 11 percent reporting they had leftovers and 6 percent saying they might take them if they had future infections. Speaking on European Antibiotics Awareness Day, Dr McNulty said that while the numbers might appear small, they could translate into large numbers given that 30 percent of people take antibiotics every year. She said \"There is evidence that the more antibiotics you have, the more likely you are to develop resistance. And you\'re also more likely to develop antibiotic-related diarrhoea.\" However, 70 percent were aware of the problem of antibiotic resistance in hospitals, and a similar number were aware that they or their family could be affected.The HPA says health professionals must learn to resist demands from patients for treatments they know have little or no effect on coughs and colds.It found 97 percent of those questioned said that the last time they had asked their GP or nurse for an antibiotic, they were prescribed one.The Department of Health issued fresh guidance on antibiotic prescribing in hospitals today, with doctors and nurses being urged to \"think twice\" before offering them to patients. Dr Clare Gerada, chair of the Royal College of GPs, said \"Antibiotics are a wonderful thing when used properly, but they are not a cure-all for every condition, and should not be seen, or used, as such\".