The use of antibiotics to treat bacterial infections causes a continual and vicious cycle in which antibiotic treatment leads to the emergence and spread of resistant strains, forcing the use of additional drugs leading to further multi-drug resistance.
But what if it doesn’t have to be that way?
In a presentation at the American Society for Biochemistry and Molecular Biology’s annual meeting, titled “Driving backwards the evolution of antibiotic resistance,” Harvard researcher Roy Kishony discussed his recent work showing that some drug combinations can stop or even reverse the normal trend, favoring bacteria that do not develop resistance.
“Normally, when clinicians administer a multi-drug regimen, they do so because the drugs act synergistically and speed up bacterial killing,” Kishony explains. However, Kishony’s laboratory has focused on the opposite phenomenon: antibiotic interactions that have a suppressive effect, namely when the combined inhibitory effect of using the two drugs together is weaker than that of one of the drugs alone.
Kishony and his team identified the suppressive interaction in E. coli, discovering that a combination of tetracycline – which prevents bacteria from making proteins – and ciprofloxacin – which prevents them from copying their DNA – was not as good as slowing down bacterial growth as one of the antibiotics (ciprofloxacin) by itself.
Kishony notes that this suppressive interaction can halt bacterial evolution, because any bacteria that develop a resistance to tetracycline will lose its suppressive effect against ciprofloxacin and die off; therefore, in a population the bacteria that remain non-resistant become the dominant strain.
