LONDON Patients whose doctors over-prescribe antibiotics may develop drug resistance that lasts up to a year, putting them and the population at risk when more serious treatment is needed, scientists said on Wednesday.
The more antibiotics are prescribed for coughs and flu-like illnesses, or urine infections, the more bacteria become resistant in a vicious cycle, said British researchers who analyzed 24 previous studies of antibiotic resistance.
"The effect is greatest in the month immediately after treatment, but may last for up to a year, and this residual effect may be a driver for high levels of resistance in the community," said Alastair Hay, a consultant senior lecturer in primary health care at Bristol University, who led the research.
Medical experts say overuse of antibiotics in Europe, the United States and other wealthy regions is building widespread resistance in and threatening vital medical treatments from hip replacements and cancer therapies, to intensive care.
Hay said his study showed how individual resistance was building up, and how that then translated into community- or population-wide problems.
Antibiotics are needed in all these treatments to prevent bacterial infection, but can be rendered useless if they are used so widely that bugs develop ways to outwit them.
Multi drug-resistant bacteria are a growing problem in hospitals worldwide, marked by the rise of "superbug" infections like methicillin-resistant Staphyloccus aureus (MRSA).
But Hay, whose study was published in the British Medical Journal, said the problem of antibiotic resistance is often ignored in doctors' clinics, despite the fact that some 80 percent of antibiotic prescriptions come from family doctors.
"Up until now, the majority of the evidence has been at a population level, so it was very easy -- both for clinicians and patients -- to say 'this isn't my problem' or say 'just one more antibiotic isn't going to make a difference'," Hay said.
"But the more we prescribe, the more the bacteria become resistant. And really the only way of turning that vicious cycle into a virtuous circle is to only prescribe when it is absolutely necessary in the first place."
Experts say the annual cost in the United States of treating infections traceable to just six drug-resistant bacteria is more than $1.87 billion -- more than the yearly cost of treating flu.
In the European Union, added costs and loss of productivity as a result of antibiotic resistance are estimated at around 1.5 billion euros ($1.85 billion) a year.
In a commentary on the study, Chantal Morel and Elias Mossialos, specialists in economics and health policy from the London School of Economics, said it showed how great the need was for new classes antibiotics to be developed.
Morel and Mossialos said financial incentives should be used to persuade drug companies to invest in research to find, test and develop new antibiotics.
"In view of the rapid growth of antibiotic resistance...the intricacies of the antibiotics market, and the cost savings from improved treatment, there is a public health well as economic justification for intervention," they wrote.
(Editing by Reed Stevenson)