Dressings Containing Ag Oxysalts™ Effectively Disrupt Wound Biofilms In Vivo

Biofilms are a major contributing factor to the failure of wounds to heal. In a biofilm, bacteria are protected by a matrix of extracellular polymeric substance and are more tolerant to antimicrobial therapies. Silver dressings are commonly used to treat wound infections, however their efficacy against biofilms vary. Here we compared the efficacy of dressings containing Ag Oxysalts™, which produce higher oxidative states of silver (Ag2+ and Ag3+), to dressings containing singly ionic silver (Ag1+) against biofilm infected wounds.

P. aeruginosa or S. aureus biofilms infected murine wounds were treated with control or silver dressings. After 3 days wounds were harvested and wound area and re-epithelialisation quantified. Viable bacteria were quantified by standard plate counts and biofilms visualized by scanning electron microscopy (SEM). The extracellular polymeric substance was visualized by staining intracellular and extracellular DNA with Syto 60 and Toto 1.

Ag Oxysalt™ dressings significantly reduced wound area (32%-42%) and increased re-epithelialisation (31%-44%) compared to control and other silver dressings tested. All silver dressings reduced viable bacteria counts by 1 to 4 logs and SEM showed visibly less bacteria and EPS within Ag Oxysalt™ treated wounds. In addition, a reduction in extracellular DNA was observed in all wounds treated with silver dressings when compared to the control.

Ag Oxysalt™ dressings promoted healing of biofilm infected wounds, effectively reducing bioburden and the extracellular DNA associated with the biofilm matrix.

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