In this study, we report a novel method of suppression of Escherichia coli (E.coli) culture vitality using biocompatible silicon nanoparticles as sensitizers of cavitation processes of therapeutic ultrasound irradiation (USI). Silicon nanoparticles without (SiNPs) and with polysaccharide (dextran) coating (DSiNPs) were used. Both types of nanoparticles were almost non-toxic to mammalian cells up to concentration of 2 mg/ml. The combined treatment of nanoparticles at 1 W/cm2 USI resulted in reduction of bacterial viability upto 35% and 72% for SiNPs and DSiNPs, respectively. The better results for DSiNPS can be explained by the fact that biopolymer shell of polysaccharide provides a stronger adhesion of nanoparticles with bacteria surface. TEM microphotographs showed that the bacteria lipid shell are noticed to be partially perforated after combined treatment of DSiNPs and USI, that can be explained by the lysis of bacterial membrane due the cavitation sensitized by the nanoparticles. Furthermore, we have shown the in vitro possibility to achieved the 100% inhibition of E.coli bacteria colonies growth by couple treatment of DSiNPs and USI with increased intensity upto 3 W/cm2. The observed results reveal a novel application of SiNPs as a promising antimicrobial agent.