Targeted Cascade Therapy with Multifunctional Nanovesicles Engineered from Synergistic Antibacterial Agents for Precision Treatment of Multidrug‐Resistant Infections and Biofilms

Multidrug-resistant (MDR) Staphylococcus aureus (S. aureus), classified as a high-priority tier II pathogen, poses a glowing threat to global health. Single-mode antibacterial approaches often fall short of achieving optimal effects, necessitating the development of combination therapies. To address these challenges, pH-responsive antibacterial nanovesicles, termed DAClLy, are developed by integrating targeting ligand and multiple antimicrobial agents with complementary modes of action to target MDR bacteria with enhanced efficacy while minimizing adverse effects. DAClLy are engineered through the complexation of sulfonium-ion-bearing antibacterial polypeptoids, and primary amine-containing polypeptoids modified with 2,3-dimethyl maleic anhydride, encapsulating lysostaphin, a bacteriolytic enzyme. Upon reaching the acidic microenvironment of bacterial infections, the DAClLy vesicles disassemble, releasing their antimicrobial components. The released lysostaphin degrades bacterial cell walls, while the polypeptoids synergistically disrupt bacterial membranes, resulting in a multi-action bactericidal effect. This synergistic mechanism demonstrates remarkable efficacy against MDR S. aureus, including its resilient biofilm formations. In vivo studies have shown that the DAClLy vesicles exhibit potent antibacterial activity against MDR S. aureus-induced skin and lung infections. The nanovesicles effectively penetrate the lung mucus barrier, addressing both surface-level and deep-tissue infections. By integrating multiple strategies, DAClLy offers a promising therapeutic strategy to combat MDR pathogens across diverse tissue contexts.