Pterostilbene synergizes with colistin against multidrug-resistant bacteria via iron chelation and membrane disruption, and promotes gut health restoration in weaned piglets

The emergence of polymyxin-resistant Gram-negative pathogens has severely compromised colistin (COL) efficacy in veterinary therapy, posing critical challenges to animal health and food safety. Here, we show that pterostilbene (PTE), a dietary phenolic compound abundant in blueberries and grapes, effectively restores and enhances the antibacterial activity of COL. PTE acts synergistically with COL against multidrug-resistant strains, eliminates metabolically dormant persister cells and suppresses biofilm formation. Mechanistically, PTE chelates ferrous iron to deplete intracellular iron pools, while unexpectedly inhibiting iron-driven lipid peroxidation and preserving membrane potential. This disruption of iron homeostasis stimulates ATP generation but, when combined with COL, triggers a futile metabolic cycle that leads to severe ATP leakage. Additionally, PTE compromises outer membrane integrity and increases inner membrane phospholipid susceptibility, augmenting COL-induced lethal damage. In a Galleria mellonella infection model, the PTE-COL combination significantly improves survival. Moreover, in weaned piglets, PTE supplementation promotes restoration of a balanced gut microbiota and reduces pathogen abundance. These results highlight PTE as a safe, food-compatible adjuvant that resensitizes resistant bacteria to COL via a multi-target mechanism, offering a sustainable strategy for controlling resistant infections at the food-animal interface.