A synthetic polymer clears infections in mice caused by a multiple-drug-resistant bacterium.

Gram-negative bacteria are particularly hard to kill once they become drug resistant. To target them, Eric Reynolds, Greg Qiao and their colleagues at the University of Melbourne in Australia designed star-shaped antimicrobial nanoparticles made of amino acids. The molecules killed several common Gram-negative pathogens in culture, and cleared infections in mice caused by Acinetobacter baumannii, which is resistant to several antibiotics. When cultured with sublethal concentrations of the nanoparticles for 24 days, A. baumannii did not grow resistant over 600 generations.

The nanoparticles hit multiple targets — disrupting the bacterial outer membrane and the exchange of ions, and inducing pathways for cell death — and are likely to be more stable and less toxic than most antimicrobials under development, the authors say.

Nature Microbiol. 1, 16162 (2016)