The growing resistance to antimicrobial drugs has significantly complicated the effective treatment of infections, prompting global efforts to address this crisis. The World Health Organization (WHO) has prioritized pathogenic bacteria in a recent report to guide research and public health initiatives. This report underscores the critical role of biofilm-associated infections and highlights the need for innovative strategies to combat multidrug-resistant microorganisms. Among such strategies, the green synthesis of metallic nanoparticles has emerged as a promising approach. This environmentally friendly method yields biocompatible materials with significant biomedical potential. Biogenic zinc nanoparticles (ZnNPs), synthesized via eco-friendly methods using Pseudomonas aeruginosa, offer a promising approach for biofilm eradication and combating microbial resistance. This study evaluates the antibacterial and antibiofilm activities of biogenic ZnNPs against clinically relevant microorganisms, including biofilm-forming bacterial strains such as Staphylococcus aureus and Escherichia coli.

Antimicrobial effects were assessed using broth microdilution and time-kill assays. Biofilm formation and eradication were evaluated through crystal violet staining, resazurin assays, and colony-forming unit quantification. Additionally, the oxidative and nitrosative stress toxicity mechanisms triggered by ZnNPs, particularly those related to cellular stress, were investigated. The results demonstrated that ZnNPs exhibit concentration-dependent inhibitory effects on both prokaryotic microorganisms. ZnNPs inhibited biofilm formation by up to 50% in E. coli and yeast species and up to 80% in S. aureus. These antibiofilm activities were attributed to disruptions in cellular stress metabolism, primarily driven by nitrosative stress through enhanced production of reactive nitrogen intermediates.

The findings reveal significant antimicrobial activity, effectively targeting bacterial biofilms. These results demonstrate the potential of ZnNPs as an innovative strategy for managing biofilm-related complications. Furthermore, they underscore the importance of developing sustainable approaches to address the growing challenge of antimicrobial resistance, providing a strong foundation for future advancements in antimicrobial therapies.