Combinations of three antibiotics could be key to beating antimicrobial resistance

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Combining three antibiotics could help to tackle antibiotic resistance, according to biologists. 

Resistance to antibiotics can be offset by combining three antibiotics that interact well together, even when the individual three, or combinations between two of them, might not be very effective in fighting harmful bacteria. This is according to a study by UCLA life scientists which was published in the journal Royal Society Interface.

The need for new antibiotics is urgent. Around 700,000 people each year die from drug-resistant bacterial infections. Common infections and routine surgery could eventually be fatal if new antibiotic treatments are not found.

The research found that combinations of three different antibiotics from a group of 14 drugs can often overcome bacteria’s resistance to antibiotics, even if they are ineffective on their own or when combined with one other.

The researchers grew E. coli bacteria in a laboratory and treated the samples with combinations of one, two and three antibiotics from the group of drugs, then studied how effectively every possible combination of drugs worked to kill the bacteria.

Some combinations killed 100% of the bacteria, including 94 of the 364 three-drug groupings the researchers tested. 

Elif Tekin, the paper’s lead author and a UCLA graduate student, helped to design a framework that enabled the scientists to determine when adding a third antibiotic was producing new effects that combinations of two drugs could not achieve.

“Three antibiotics can change the dynamic,” she said. 

Different classes of antibiotics use different mechanisms to fight bacteria. Little previous research indicating that combinations of three antibiotics might work better together than any combination of two has been carried out.

The researchers said that the findings could be one weapon to fight what has become a major public health risk, but overcoming drug resistance would require attacking the problem from all sides.

Senior author and UCLA assistant professor of ecology and evolutionary biology, Pamela Yeh, said: “We need sound policy to stop the overuse of antibiotics, doctors to prescribe antibiotics wisely, agriculture to stop overusing antibiotics and researchers to develop new antibiotics. We think our contribution will buy time for researchers to better leverage existing drugs and for policymakers to develop better policy about the use of antibiotics.”