Microbiology: Antibiotic-resistant bacteria meet their match?

Researchers may have found a way of keeping drug-resistant bacteria in check — certain combinations of antibiotics favour the growth of non-resistant strains at the expense of resistant ones. The finding may help combat the spread of these microbes, as well as shed light on microbial ecology and evolution.
Antagonistic drug combinations, in which the drugs' cumulative effects are less than when they are given separately, show such effects, say Roy Kishony and colleagues. At sublethal concentrations, a mixture of doxycycline and ciprofloxacin preferentially selects for wild-type Escherichia coli bacteria over that of a doxycyline-resistant strain in a laboratory culture.
The finding is surprising and counter-intuitive, as the use of antibiotic drugs is responsible for the generation and selection of resistant bacterial pathogen strains. But this study shows that, with the right combinations and concentrations, non-resistant bacterial strains can be selected for.
CONTACT
Roy Kishony (Harvard Medical School, Boston, MA, USA)
Tel: +1 617 432 6390; E-mail: roy_kishony@hms.harvard.edu