Researchers from University College London and Imperial College London have elucidated the mechanism by which polymyxin B, a last-resort antibiotic against multidrug-resistant Gram-negative bacteria, kills bacteria. The antibiotic disrupts the outer bacterial membrane by inducing rapid formation and shedding of membrane protrusions, a process that requires bacterial metabolic activity. Dormant bacteria evade killing as they do not actively produce membrane armor. This discovery, published in Nature Microbiology, offers new insights into antibiotic resistance and potential strategies to counter persistent infections.