BackgroundAgainst a variety of antimicrobial resistant pathogens, the scientists attempted substitution of antimicrobial medicine with various nanoparticles and plant-based antibacterial substances.ObjectivesThe aim of this study was to assess the antibacterial effects of silver nanoparticles solely and in combination with Zataria multiflora essential oil and methanolic extract on some photogenic bacteria.MethodsMinimum inhibitory concentrations (MICs) and fractional inhibitory concentrations (FICs) of plant essential oil, methanolic extract, and silver nanoparticles against bacteria were evaluated using the broth microdilution method and check board microtiter assays.ResultsThe results of the experiment showed that the MIC and minimal bacterial concentration (MBC) values of Ag-NPs against all strains were in the range of 15.625 - 500 µg/mL, and values for the essential oil and plant extract were in the range of 1.56 - 100 mg/mL.ConclusionsSilver nanoparticles were observed to have additive effects with essential oil against Staphylococcus epidermidis and S. aureus. The obtained results suggest the need for further investigations of the antibacterial effects of the combination of silver nanoparticles with other plant extracts and essential oils.

Background and Objective: The spread of drug resistance in bacteria have prompted researchers to seek suitable alternative for antimicrobial drugs among various medicinal plants and nanoparticles. The aim of this study was to evaluate the effect of silver nanoparticles alone and in combination with methanol extract of Zataria multiflora on five Gram-positive and Gram-negative bacteria. Methods: Different concentrations of the nanoparticles and extract alone or in combination with each other were tested against the bacteria, using well diffusion method. Three concentration levels (lowest, average and highest) were prepared form the nanoparticles and the extract for the combination, and finally nine different combinations were prepared. Results: The extract and nanoparticles showed inhibitory effects against all the tested bacteria. The maximum diameter of growth inhibition zone in the presence of the extract and nanoparticles were observed in Streptococcus pyogenes (35.6mm) and methicillinresistant Staphylococcus aureus (20.6mm), respectively. The maximum diameter of growth inhibition zone for the combination was measured in S. pyogenes (31mm). Conclusion: The combination of low concentrations of the plant extract and nanoparticles are more effective against bacteria, but the combination of their high concentrations reduce the antibacterial effects in some cases.