Resident in Small Animal Surgery Purdue University College of Veterinary Medicine
Nanoparticulate silver (AgNP) is a versatile product with established bactericidal activity against a range of bacteria. The objective of this study was to establish the in vitro bactericidal activity of AgNP against Methicillin-resistant Staphylococcus pseudintermedius (MRSP) and Escherichia coli using commercially available AgNP. It was hypothesized that antibacterial activity would be demonstrated against both MRSP and E. coli. Meuller-Hinton broth, inoculated with bacteria at a variety of concentrations, was incubated with 10 µg/ml AgNP (citrate stabilized, 10 nm diameter) in a microdilution assay plate for 18-24 hours at 37°C, sub-cultured to blood agar plates, and incubated for a further 18-24 hours at 37°C for determination of colony forming units (CFU). Exposure to 10 µg/ml AgNP greatly reduced bacterial growth up to a bacterial concentration of 10<sup>2</sup> CFU/ml for MRSP and 10<sup>4</sup> CFU/ml for E. coli. The reduction in bacterial burden shows strong antimicrobial activity of AgNP against both species at a concentration of 10 µg/ml. This study did not assess the effect of wound bed characteristics on the activity of AgNP. AgNP exhibits strong antimicrobial activity against MRSP and E. coli and has the potential for use in veterinary wound care products designed for use in infected wounds which cannot be left open.
