Antibiotic resistance could be tackled by giving people a combination of drugs which no longer work on their own, a new study suggests.

Scientists have discovered thousands of drug cocktails which can fight bacteria even though bacteria may have grown resistant to them individually

Previously it was thought that the downside of combining antibiotics outweigh the benefit because of dangerous interactions.

But the University of California discovered around 8,000 combinations of four and five pills that are effective, a breakthrough which researchers say could be a major step forward in protecting public health.

"I was blown away by how many effective combinations there are as we increased the number of drugs," said Van Savage, the study's other senior author and a UCLA professor of ecology and evolutionary biology and of biomathematics.

"People may think they know how drug combinations will interact, but they really don't."

Health experts have warned that within 20 years even routine operations such as hip replacements and organ transplants could be deadly because of the risk of infection.