Metal and metal oxide colloidal nanoparticles are increasingly used as an alternative to antibiotics because of their many advantages (in comparison to antibiotics) for treatment and prevention of bacterial infections. The most popular colloidal nanoparticles are silver, zinc oxide and titanium dioxide nanoparticles because they are used in various fields such as biotechnology and biomedicine. Escherichia coli (E.coli) is the most finely understood and extensively studied free-living organism on our planet. However, despite being the most extensively studied organism, E.coli is still to this day a very common cause of diseases of various organs and therefore E.coli is a very interesting model organism for this study. Resistance to antibiotics emerges in bacteria due to genetic mutations and consecutive selection of resistant mutants through selective pressure of antibiotics and because of that antibiotic resistance has become one of the leading problems in modern medicine. Therefore, currently available options (such as antibiotics) against bacterial infections are limited and it is advised to turn to new and improved antimicrobial agents. Metal and metal oxide colloidal nanoparticles are exactly that, the new and improved antimicrobial agents. MIC and MBC values of silver, zinc oxide and titanium colloidal nanoparticles against E.coli ATCC 10536 suggest that these nanoparticles are very potent antimicrobial agents with silver nanoparticles being the most potent of them. A mixture of nanoparticles (0.794 ppm of silver, 683.217 ppm of titanium dioxide and 15.989 ppm of zinc oxide) was prepared to determine a possible synergism between them. Results suggest that there is no synergism observed between silver, zinc oxide and titanium colloidal nanoparticles in the mixture and that there is no statistically significant difference in terms of antimicrobial efficiency against the two E.coli strains (ATCC 10536 i ESBL+ MFBF 12794). Lastly, antimicrobial efficiency of a textile fabric impregnated with the mixture of nanoparticles was evaluated using the time-kill method. Results suggest that after 12 hours of incubation there were no growth of bacterial colonies observed (complete reduction of bacterial colonies) for both E.coli strains. However, no statistically significant difference in terms of reduction of bacterial colonies was observed between the two E.coli strains.