Here's a very interesting study from 2013 on the comparative antibacterial effects of AgNP's against six bacterial strains: Gram-negative Escherichia coli, Pseudomonas fluorescens, P. putidaand P. aeruginosa and Gram-positive Bacillus subtilis and Staphylococcus aureus. The results are certainly worth reading about.
"Herein, we demonstrated that the direct contact between bacterial cell and AgNPs' surface enhanced the toxicity of nanosilver. More specifically, cell-NP contact increased the cellular uptake of particle-associated Ag ions – the single and ultimate cause of toxicity."
