The Anti-biofilm Efficacy of Colloidal Silver Nanoparticles against Clinical Isolate of Staphylococcus epidermidis Biofilm

The key factor in the pathogenicity of Staphylococcus epidermidis is colonization and multilayer biofilms formation. Biofilm creates a barrier against antimicrobial agents and prevents antibiotic function. In addition, increase of resistance to antibiotics is one of the main problems with their usage. Today, the use of nanoparticles has been widely considered due to their antimicrobial properties and low toxicity. The purpose of this study was to evaluate the antimicrobial activity of silver nanoparticles against biofilms caused by Staphylococcus epidermidis.

In this study, 90 strains of Staphylococcus epidermidis including 50 clinical isolates and 40 strains isolated from the carriers were studied. Biofilm formation experiments were performed by using microtiter plate and stained by crystal violet. Minimum inhibitory concentration (MIC) was achieved by Agar well diffusion method and microplates. The oxacillin resistance was evaluated by disk diffusion method.

The silver nanoparticles had an anti-biofilm activity of 3.9 ppm and increased at a higher concentration of 7.8 ppm. At the concentration of 15.62 ppm, the biofilm was destroyed. A total of 24 isolates were resistant to oxacillin.

The results of this study indicated that colloidal nanoparticles against Staphylococcus epidermidis have a bactericidal effect, and in concentrations below the MIC, it can inhibit biofilm formation caused by this organism.