It is becoming increasingly clear that a happy, healthy microbiome is fundamentally important to human health. Perturbation of the microbiome – especially in the gut – is responsible for C. difficile infection and probably many other diseases directly and indirectly linked to the gut. This has led to a move towards microbiome-sparing approaches to therapy. Faecal microbiota transplantation is one such approach, which happens to be spectacularly effective for treating recurrent CDI and may also be useful for decolonising carriers of resistant Gram-negative bacteria. A related approach is using a ‘competitive exclusion’ to reduce the level of contamination of hospital surface with hospital pathogens by seeding the surfaces with live Bacillus sp. spores. But wouldn’t it be great if there was a way to specifically target antibiotic-resistant bacteria and leave yourself with an antibiotic-susceptible population?