Green Synthesized Zinc Oxide Nanoparticles as Antibacterial and Antibiofilm Agents against Multidrug-Resistant ESKAPE Pathogens

Abstract

A major obstacle to successful antimicrobial therapy is the rising incidence of multidrug-resistant (MDR) bacterial infections, especially those brought on by ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.). The development of biofilms increases bacterial resistance to antibiotics and fuels chronic infections. Green-synthesised zinc oxide nanoparticles (ZnO NPs), made from the leaf extract of Bauhinia variegata, were tested for their antibacterial and antibiofilm properties against clinically isolated MDR ESKAPE pathogens both alone and in combination with specific antibiotics. Agar well diffusion, checkerboard synergy assays, broth microdilution, and microtiter plate biofilm inhibition techniques were used to measure the antimicrobial activity. With minimum inhibitory concentrations (MICs) ranging from 15.64 to 500 µg/mL, ZnO NPs demonstrated broad-spectrum antibacterial activity. Pseudomonas aeruginosa had the lowest MIC. ZnO NPs and imipenem were found to work synergistically against several isolates, and ZnO NPs and gentamicin were found to work synergistically against Enterococcus faecium and Enterobacter species. The range of biofilm inhibition was 26.3% to 80%, with Enterobacter spp. treated with ZnO NPs and gentamicin showing the largest decrease. These results show that green-synthesized ZnO nanoparticles have strong antibacterial and antibiofilm potential and can boost the effectiveness of traditional antibiotics, indicating their potential as supplemental agents in MDR bacterial infection management strategies.