Giving patients a combination of four or five antibiotics may be the best way of tackling killer superbugs, researchers believe.
For years, scientists have warned taking more than one of the drugs at the same time would prove useless in combating bacterial infections.
But a new study debunks the theory and offers hope of ‘promising’ new route in the face of the ever-growing threat of antibiotic resistance.
Biologists at the University of California, Los Angeles, who made the discovery, say combinations will work if the drugs target bacteria in different ways.
Britain’s chief medical officer, Dame Sally Davies has previously warned that the threat of antibiotic resistance is as severe as terrorism and global warming.
For years, scientists have warned taking more than one antibiotic at the same time would prove useless in combating bacterial infections
The UCLA team assessed eight antibiotics. They stumbled across 8,119 combinations of four or five antibiotics that, when taken together, performed better than expected.
Dr Pamela Yeh, senior author of the scientific paper, said: ‘We’re offering an alternative that looks very promising.
‘We shouldn’t limit ourselves to just single drugs or two-drug combinations in our medical toolbox.
‘We expect several of these combinations, or more, will work much better than existing antibiotics.’
The medical community has traditionally believed combining more than two drugs to fight harmful bacteria would yield diminishing returns.
The prevailing theory is the incremental benefits of combining three or more drugs would be too small to matter.
While fears have also been raised that the interactions among the drugs would cause their benefits to cancel one another out.
But the new study, published in the journal npj Systems Biology and Applications, challenges the theory.
In laboratory tests, Dr Yeh and colleagues analysed how every possible four and five-drug combinations worked against E. coli.
A total of 18,278 combinations were tested in total against the bacteria, based on varying dosages of each drug – which work in different ways.
They expected some combinations would be effective at killing the bug, but were startled by how many potent combinations they found.
For every combination they tested, the researchers first predicted how effective they thought it would be in stopping the growth of E. coli.
Among the four-drug combinations, there were 1,676 groupings that performed better than they expected in the laboratory trial.
And among the five-drug combinations, 6,443 groupings proved to be more effective than Dr Yeh and her team expected.
However, 7,530 four and five drug combinations proved less effective than the team predicted, according to fellow senior author Professor Van Savage.
He said: ‘I was blown away by how many effective combinations there are as we increased the number of drugs.
‘People may think they know how drug combinations will interact, but they really don’t.’
Professor Savage suggested the drug combinations were effective, at least partly, because they have different ways of targeting E. coli.
He said: ‘Some drugs attack the cell walls, others attack the DNA inside. It’s like attacking a castle or fortress.
‘Combining different methods of attacking may be more effective than just a single approach.’
The researchers have now warned they are years away from having the combinations thoroughly evaluated as possible treatments in humans.
Dr Michael Kurilla, director of the Division of Clinical Innovation at the National Institutes of Health, praised the discovery.
He said the ability to more ‘judiciously’ use combinations of existing antibiotics that are losing potency is welcome.
Dr Kurilla warned the emergence of antibiotic resistance is threatening to ‘turn back health care to the pre-antibiotic era’.