We are continually in an evolutionary arms race with bacteria. As we develop new antibiotics, they develop resistance, and so it goes on until some of our treatments no longer work. Superbugs and antimicrobial resistance (AMR) are a huge global health problem. So what do you do when your medicines are ineffective? The answer for some researchers is to build their own biological weapons. A team including experts from the University of Oxford in the UK has developed a way to create specialized cells that hunt down and kill drug-resistant germs.