Evaluation of Nanosilver Solution Stability against Streptococcus mutans, Staphylococcus aureus and Pseudomonas aeruginosa

Background: Nanosilver compounds are admired in different fields of medicine and industry, due to their unique antibacterial properties. Maximum contact of silver particles in nanosilver suspension causes increasing antibacterial effect of this compound. Objectives: The aim of this study was to evaluate the stability of antibacterial properties of nanosilver solution during a period of 9 months against Streptococcus mutans, Staphylococcus aureus and Pseudomonas aeruginosa. Materials and methods: In this in vitro study, the antibacterial effect of serial concentrations of nanosilver solution and amoxicillin antibiotic as control group on the standard bacteria S. mutans, S. aureus and P. aeruginosa were measured in 0-3-6-9 month period by Disc diffusion methods. Results: The antibacterial activity and stability of nanosilver solution in comparison with amoxicillin antibiotic were measured and the results were examined by t-test statistical analysis. During 9 months, no significant changes were seen in antibacterial activity of nanosilver solution (4000 mu g.ml(-1)), except for S. mutans. In other concentrations of nanosilver solution and amoxicillin, reduction of antibacterial activity was observed. Conclusions: Antibacterial activity of 4000 mu g.ml(-1) nanosilver was stable in a 9 month duration but reduction of antibacterial activity in lower nanosilver concentrations and amoxicillin were significant in the same time period.