The emergence of new infectious agents is a potential risk associated with genetic manipulation and field cultivation of genetically modified organisms and constitutes a new challenge in molecular epidemiology. The main objective of the current study was to synthesize silver nanoparticles and evaluate the antibacterial activity of these nanoparticles. E. coli and Enterococcus sp. were isolated from wastewater samples collected from Kalamu River. The preliminary characterization of silver nanoparticles was carried out using UV-visible spectrophotometer. Noble metals, such as silver nanoparticles, exhibit unique and adjustable optical properties due to their external plasmon resonance. The reduction of silver ions was monitored by measuring the UV-visible spectrum of the solutions after dilution of a small aliquot (0.2 mL) of the aqueous component. The antibiotic susceptibility test results confirmed the inactivity of these antibiotics tested against the wild strain of Enteroccocus sp. The synthesized silver nanoparticles displayed a good antibacterial activity against Enterococcus sp. The synthesis of silver nanoparticles is designed precisely to alleviate this situation; and these results provide a strong evidence that silver nanoparticles can be used to fight antibiotic-resistant bacteria.