Pterostilbene Eliminates MRSA Independent of Metabolic State and Effectively Prevents Biofilm Formation in Milk Matrices

The relentless spread of antimicrobial resistance poses a severe threat to global public health, food safety, and environmental security. Natural products with potent antimicrobial activity offer prospective substitutes for traditional antibiotics and chemical preservatives. Here, we demonstrate that pterostilbene (PT), a natural dietary compound, exhibits rapid lytic activity against methicillin-resistant <i>Staphylococcus aureus</i> (MRSA). PT displayed metabolism-independent bactericidal effects, effectively eradicating dormant persister cells within one hour, though its activity was partially attenuated under anaerobic conditions. Mechanistically, PT disrupted membrane integrity by increasing permeability, dissipating membrane potential, depleting cellular ATP, and suppressing reactive oxygen species (ROS) generation. Its efficacy was modulated by membrane phospholipid composition, with phosphatidylglycerol (PG) and cardiolipin (CL) critically influencing antimicrobial potency. Crucially, PT robustly inhibited MRSA biofilm formation in milk. These findings highlight PT's potential as a structurally stable, natural antimicrobial for controlling resilient MRSA, particularly against biofilm-associated and persister subpopulations in food systems.