Lethal permeabilization of host bacteria to small-molecule compounds during phage penetration

Tailed phages (Caudoviricetes) inject their double-stranded linear genomic DNA across the bacterial envelope to initiate infection. During this DNA entry process, ionic fluxes and membrane depolarization may occur, potentially leading to increased vulnerability to antibiotic molecules. Here, we report that phage DNA translocation combined with certain small molecules triggers rapid and phage-specific cell permeabilization leading to bacterial growth arrest. We use live-cell fluorescence microscopy to visualize the accumulation of otherwise excluded compounds such as anthracyclines and propidium iodide. We show that the influx and accumulation of these compounds depend on both the presence of an inner-membrane receptor and persistent membrane depolarization. We further demonstrate that phage-induced permeabilization enhances the efficacy of certain antibiotics, enabling synergistic elimination of antibiotic-resistant bacteria. Our results provide a mechanistic foundation for combining phages with small-molecule therapeutics and offer insights into how phage entry relies on and alters host physiology. Tailed phages inject their genomic DNA across the bacterial envelope to initiate infection. Here, the authors show that phage DNA translocation, combined with certain small molecules, triggers rapid and phage-specific cell permeabilization leading to bacterial growth arrest. We thank KC Huang, Pushkar Lele, Jason Gill, and the Center for Phage Technology for sharing strains. We are grateful to Alan Davidson, Karen Maxwell, and Annie Si Cong Li for sending Pseudomonas phages and thoughtful discussion on early versions of ... [1679 chars]