The Inhibition Activity of Silver Nanoparticles Compared with D-Glycin and Imipenem Effect on the Biofilm Formation by Food-origin Salmonella isolates

Since decades silver was depended worldwide as a treatment to a lot of diseases ranging from burn infections, anthrax, and typhoid fever to bacterial conjunctivitis in stillbirth, but its effectiveness against biofilms is still undetermined. Salmonella is a major cause of food poisoning outbreaks especially in the third world countries. Thus, in the present study; the antimicrobial activity of silver nanoparticles (Ag- NPs) against Salmonella enterica biofilm was examined; their activity was compared with amino acid; D-Glycin and imipenem antibiotic. The result of the study revealed that Ag-NPs exhibited considerable antimicrobial property against Salmonella enterica biofilm where the minimum inhibitory concentration (MIC) was found at 50 μg/ml while MIC of D-glycin and imipenem were 50mM and 4μg/ml respectively. The isolates ability to form biofilm was assayed using the tissue culture plate (TCP) assay, all the isolates were biofilm producers but with a different thickness degrees. It was found that both of Ag-NPs and imipenem inhibited Salmonella biofilm formation, but the inhibition by Ag-NPs was more than the antibiotic imipenem, whereas D-Glycin increased the ability of Salmonella isolates to form biofilm.