Nosocomial and Healthcare Associated Infections

The increase of resistant strains is a major problem in these days. Researchers are testing new antimicrobials, inclusive compounds

produced by nanotechnology. Salmonella is a genus of bacteria that are a major cause of foodborne illness in the world and

are transmitted through contaminated food. In this study, we tested biologically synthesized silver nanoparticles (AgNPbio) against

Salmonella enterica. AgNPbio were prepared according to a method by Durán et al., 2005. The AgNPbio diameter and zeta potential were

determined by photon correlation spectroscopy. Minimal inhibitory concentrations (MICs) were determined by broth microdilution

assays in 96-well plates, as suggested by CLSI. The in vitro antibacterial activity of AgNPbio was examined against four reference

bacterial strains (ATCC), Staphylococcus aureus 25923, Escherichia coli 25922, Salmonella typhimuirum UK1 and Salmonella

enteritidis 13076, and 19 bacteria isolated from chicken. Minimal bactericidal concentration (MBC) was determined by sub-culturing

10 μL from the broth dilution MIC. The AgNPbio presented the size range 81.25 nm, zeta potential –36.4 mV and PI= 0.296. E. coli

and S. aureus with MIC of 39.4 μM while S. typhimuirum and S. enteritidis showed MIC value of 78.7 μM. Isolates from chicken also

showed sensitivity for AgNPbio with MIC ranged from 78.7 μM to 157.5 μM, and all bacterial strains showed the MBC≤157.5 μM. The

AgNPbio is a great alternative because it was not related to any bacterial strain naturally resistant to silver nanoparticles. Our study

suggests that the use of AgNPbio can be effective against Salmonella enterica strains, an important food pathogen.