A study on antibacterial effect of nanosilver colloidal solution against Escherichia coli isolates from human and poultry in North-West of Iran

Because of emerging resistant bacterial strains to antimicrobial agents¡ using effective alternatives such as silver nanoparticles has became unavoidable.

For the first time¡ sensitivity of 300 E.coli isolates¡ from humans¡ healthy poultry and poultry with collibacilosis¡ were evaluated to silver nanoparticles colloidal solutions with 5 and 20 nm in diameter using standard disk diffusion method in North-West of Iran. Four used concentrations of nanosilver were 40¡ 80¡ 400 and 4000 ppm. Then statistical analysis of the results was performed.

The highest rate of zone of inhibition (ZOI) in most of the two solution concentrations were related to E.coli isolates from poultry with colibacillosis. Comparing pair of different concentrations against the three groups isolates¡ no significant difference was observed between concentrations of 40 and 80 ppm using all concentration of the two solutions except the solution of 20 nm against isolates from poultry with colibacillosis. Mean of ZOI of three groups isolates using all concentrations of 5 nm colloidal solution determined statistical significant difference among them while using 20 nm nanosilver solution¡ no significant difference were observed in 40 and 80 ppm concentrations among three groups isolates.

Application of colloidal solutions of silver nanoparticles as an effective antibacterial agents against Escherichia coli isolates needs enough information about regional isolates and rate of their susceptibility and also properties of the nanosilver solutions.