Before the era of complete resistance to antibiotics due to their extensive use in poultry farms, new strategies were discovered, one of them was the use of nanoparticles to enhance the action of antibiotics. Therefore, this study was carried out to find out the antibacterial effect of silver nanoparticles (AgNPs) either separately or in combination with antibiotics. The obtained data showed the antibacterial activity of AgNPs against the tested Escherichia coli and Salmonella strains with MIC level of 0.85 µg/mL. Synergistic effects of AgNPs with antibiotics against E. coli revealed two-fold drop in MIC of ciprofloxacin and amoxicillin. Meanwhile, there was three-fold drop in MIC of gentamicin, cefotaxime and neomycin. Significant finding was observed in the case of the synergism of AgNPs with amoxicillin and gentamicin, the examined E. coli O2 resistant to amoxicillin and gentamicin became sensitive when the antibiotics were combined with AgNPs. It could be concluded that AgNPs can be easily produced by Rosemary aqueous extracts as low-cost, eco-friendly method for generating AgNPs. New generations of bactericidal compounds containing AgNPs could be successfully used in poultry farms for prevention and treating E. coli infections.