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2025 OMIG Abstract

Dual Antibacterial Silver-Vancomycin Nanoparticles for the Treatment Experimental Bacterial Endophthalmitis

Ashok Kumar, Henry Kolge, Sukhvinder Singh, Zeeshan Ahmad, Michael Yu

Department of Ophthalmology Anatomy and Visual Sciences, Kresge Eye Institute, Wayne State University, Detroit, Michigan

Purpose: The rising incidence of drug-resistant ocular pathogens underscores the urgent need for innovative therapeutic strategies. This study aimed to develop and evaluate a dual-action antibacterial nanoformulation combining silver nanoparticles with the antibiotic vancomycin for the treatment of ocular infections.

Methods: Silver nanoparticles (AgNPs) were synthesized via chemical reduction using silver nitrate and sodium citrate. These nanoparticles were subsequently loaded with vancomycin and coated with chitosan to impart a positive surface charge, resulting in three formulations: AgNPs, chitosan-coated AgNPs (CAg-NPs), and chitosan-coated AgNPs loaded with vancomycin (C-AgVan-NPs). The formulations were characterized for size, optical properties, and drug release kinetics. Antibacterial efficacy was assessed against Staphylococcus aureus, including MRSA and clinical isolates. Cytotoxicity was evaluated using human retinal Müller glia cells. In vivo efficacy was tested in a mouse model of S. aureus endophthalmitis.

Results: The nanoformulations ranged from 60 to 70 nm in size, exhibited a characteristic surface plasmon resonance peak at 450 nm, and showed efficient vancomycin loading with controlled release under acidic conditions. Antimicrobial testing revealed potent bactericidal activity, with MIC values up to four times lower than vancomycin alone. Cytotoxicity assays demonstrated minimal toxicity to human Müller glia cells. In vivo, all nanoformulations significantly reduced bacterial burden and improved clinical outcomes in the mouse model of endophthalmitis.

Conclusions: The combination of positively charged silver nanoparticles with vancomycin offers a promising therapeutic strategy for combating drug-resistant ocular infections, particularly endophthalmitis. This dual-action nanoformulation demonstrates potent antibacterial activity, controlled drug release, biocompatibility, and therapeutic efficacy in vivo