The benefits of antibiotics to both human and animal health are undisputed. However, as microbes have become increasingly resistant to antimicrobials and other drugs, scientists have become interested in new solutions to the growing superbug crisis, including the use of defensive microbes and faecal transplants. In new research, Oxford University scientists have developed a lab-based approach, creating positive co-dependent relationships between hosts and bacteria, termed ‘mutualisms’, quickly. These lab-developed bacterial relationships demonstrate how microbes can work with their hosts to prevent infection.