Green-Synthesized Silver Nanoparticles Against Acinetobacter baumannii: A Systematic Review of Antibacterial Activity, Mechanisms of Action, Toxicity, and Antibiofilm Effects.

Acinetobacter baumannii is a major multidrug-resistant nosocomial pathogen, and new antimicrobial strategies are urgently needed. Green-synthesized silver nanoparticles (AgNPs) have emerged as promising candidates because of their broad antibacterial activity and potentially improved biocompatibility. This systematic review evaluated the antibacterial effects of pure, plant-mediated AgNPs against A. baumannii isolates. PubMed, Scopus, and Web of Science were searched from database inception to October 5, 2025 according to PRISMA guidelines. Eligible studies were original English-language reports assessing pure green-synthesized AgNPs against A. baumannii. Sixty-three studies met the inclusion criteria. Green AgNPs were generally active against A. baumannii and more often showed stronger effects than the corresponding plant extracts. The most commonly proposed mechanisms were reactive oxygen species generation, membrane and cell-wall disruption, increased permeability, and damage to proteins, lipids, or DNA. Biofilm data were limited but suggested promising inhibitory potential. Toxicity findings were mixed, ranging from good biocompatibility to cytotoxicity in sensitive cell models. Plant-mediated AgNPs show credible antibacterial potential against A. baumannii, but standardized synthesis, rigorous characterization, biofilm-focused testing, and in vivo safety studies are still needed before clinical translation.