Bacteria are growing ever more resistant to antibiotics, and there are mounting fears that soon our drugs won’t be able to fight even the most common infections. In the U.S. alone, more than 2 million people a year are infected by antibiotic resistant strains and over 20,000 die as a result.

In a bid to give our drugs a second chance, researchers from the Sackler School of Medicine in Tel Aviv have engineered viruses to infect resistant bacteria with a CRISPR-Cas9 system that eliminates the genes that code for antibiotic resistance. To ensure those modified bacteria pass on their antibiotic-susceptible genes, the scientists also had the virus deliver a set of beneficial genes that encode another CRISPR sequence to defend against infection by other viruses.