In Vitro Study of the Antimicrobial Properties of a Silver Ion-Releasing Polyurethane Foam

Abstract

IntroductionThe antimicrobial properties of a silver ion (Ag+)-releasing polyurethane foam were evaluated using different microorganisms. The diffusion of Ag+ from the medium, as well as any possible cytotoxicity on human cells, was also studied. Material and methodsSilver release from V.A.C. GranuFoam Silver® was assessed by using inductively coupled plasma mass spectrometry (ICP-MS). An in vitro experimental study was designed to evaluate the bactericide capacity using lethal dose curves on Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, K. pneumoniae, Escherichia coli, Proteus mirabilis, methicillin resistant Staphylococcus aureus, Enterococcus faecium, Streptococcus pyogenes and Corynebacterium minutissimum. A cytotoxicity study was also performed on human fibroblasts. ResultsThe silver release showed an exponential curve with a stable meseta phase after 3h, with levels of 0.22–0.24mg/l. A reduction of 99.9% of all the Gram-negatives was achieved at 3h. The reduction was greater than 99% at 2h in S. pyogenes and C. minutissimum, at 6h in S. aureus and at 14h in E. faecium. In an in vivo simulation model, these reductions were achieved in 6h in the Gram negatives and 24h in the Gram positives. The silver concentrations were no cytotoxic to human fibroblasts, with no differences being observed between the cells exposed to Ag+ and the controls (P=.7). ConclusionV.A.C. Granufoam Silver® releases bactericide concentrations of Ag+ that did not damage human fibroblasts. It appears to be a good alternative for the control and prevention of local infections.