Phage therapy is the concept of using viruses (known as phage) to kill bacteria, instead of using antibiotics. Until now, experiments have largely focussed on exposing bacteria to phage in a flask. Now, researchers have developed a new way to mimic these microenvironments, in which a single bacterium would colonize a specific area. Using this method, the team found that in these microenvironments Escherichia coli, a bacterium that is often responsible for food poisoning, does not become genetically resistant to phage, and the majority of the bacterial population is killed by phage.