Silver absorption and antibacterial efficacy of silver dressings.

OBJECTIVE: To evaluate the patterns of silver release from selected sustained silver-release dressings and the protective role of proteins in wound exudate and wound scale. The bactericidal action of silver in chronic wound therapy is also examined.
METHOD: Sequential microbiological examination of wound swabs from seven patients with chronic wounds and sampling of wound exudate and wound scale. Silver content was measured using atomic absorption spectrometry. The ability of Contreet Foam to absorb exudate and release silver was studied in punch biopsy wounds in a rodent model.
RESULTS: Silver accumulation in wound exudate correlated well with its viscosity and protein content. Silver bound to wound scale and debris was approximately proportional to the silver ion release from dressings. Bacterial burden was controlled, but not eliminated, following chronic silver therapy.
CONCLUSION: Silver dressings (Acticoat-7, Actisorb Silver, Contreet Foam, Aquacel Ag and Flamazine) were found to be safe for use in chronic wound therapy. Excess silver ion is bound by wound exudate and wound scale as a protective mechanism. Silver-release dressings are not likely to result in germ-free wounds. Further studies are needed to examine potential silver resistance.