STUDY ON ANTIBACTERIAL POTENCY AND MECHANISM OF ACTION OF SILVER-NANO PARTICLES ON ESCHERICHIA COLI AS MODEL GRAM NEGATIVE BACTERIA

Backgrounds: Emergence of bacterial resistance to several antibiotic are causing serious problem in health care. Even the broad-spectrum bactericidal effect of ionic form of silver sometimes found to be ineffective; few cases are reported to ascertain the incident of silver resistance. The purpose of the study was to examine the potency and mechanistic bactericidal actions of Silver Nano particles (AgNPs) on E. coli as model gram negative bacteria. Methods: Antibacterial activity of nano-sized silver particle was investigated against E. coli, Minimum Inhibitory Concentration (MIC) of AgNPs was determined following National Committee for Clinical Laboratory Standard (NCCLS) guideline, in Mueller- Hinton (MH) broth supplemented with different concentration of AgNPs. Growth pattern of bacteria at the MIC of AgNPs was studied and the mechanism of bactericidal action of AgNPs was observed by Transmission Electron Microscopy (TEM). Results: The antimicrobial activity AgNPs were investigated in liquid system and the results are showing that AgNPs were attached on the surface of the bacterial cell membrane; probably by the surface charge attraction followed by formation pits which destroy the integrity of the bacterial cell wall, resulting in death of the bacterial cells. Conclusions: AgNPs produce strong bactericidal action event at very low concentrations because of their high surface to volume ratio and remains effective for a longer duration. So it could be an effective therapy for open wounds if applied topically.