The agent HY-133 acts specifically against Staphylococcus aureus, a bacterium that is found in the nasal microbiome of around one in three people. Colonisation is harmless in normal life, but can become a problem during operations and hospital stays. The clinical phase I ‚first-in-human‘ trial with the novel drug candidate to test safety, tolerability and efficacy began on 10 July with the recruitment of clinically healthy volunteers who tested positive for S. aureus colonisation of the nose.