Survey of Silver Nanoparticles Antibacterial Activity Against Gram-Positive and Gram-negative Bacteria in Vitro

Increasing resistance to antimicrobial agents is typically one of the main problems of health care. Control the dispersion of bacteria in different environments is a challenge in this section that to the overcome of them is essential for health and economic. In this study, nano-silver antibacterial activity was studied against Gram-positive bacteria Staphylococcus aureus and Pseudomonas aeruginosa and Gram-negative bacterium E. coli and Bacillus cereus.
Anti-bacterial properties of silver nanoparticles against bacteria were assessed using dilution method. Bacteriological tests were performed using the initial concentration of (1 -1.5× 10-5) CFU / ml of each type of bacteria. The minimum inhibitory concentration (MIC) of growth and minimum bactericidal concentration (MBC) was determined for each bacteria in the agar medium. Since the death of bacteria was studied using a double-MIC concentrations in duration of zero to 540 min and was determined the death time of each bacteria.
The results showed that MIC for bacteria of E. coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa was at a concentration of 1700, 1600, 1500, and 1600 microgram per liter of silver nanoparticles, respectively. Also, the lowest death time was obtained 4h, for Bacillus cereus bacteria.
Based on the results of this study, bacteria E. coli showed the lowest sensitivity and Staphylococcus aureus the greatest sensitivity to silver nanoparticles.