In Vitro Determination of the Mode of Action of an Enhanced Antimicrobial Hydrofiber Dressing

Aim: The development of bioburden in chronic, non-healing wounds is now acknowledged to be a precursor to wound infection and a cause of delayed healing. A new enhanced antimicrobial silver-containing Hydrofiber wound dressing (AAA) has been developed to more effectively kill microorganisms associated with wound bioburden. This study aimed to compare AAA dressing antimicrobial effectiveness against various standard silver-containing wound dressings and examine its mode of action. 

Method: A number of in vitro bioburden test models of increasing complexity were used to culture bioburden of wound-relevant pathogens, before exposure to test dressings. Confocal laser scanning microscopy with Live-Dead™ viable staining, and measurement of total viable counts of the bioburden microorganisms, were conducted to visualize and quantify the antimicrobial effect of the test dressings. Staining of the extracellular constituents of surface-attached bioburden was also conducted to further examine the mode of action of the AAA dressing.

Results / Discussion:  Live-Dead staining and viable counting of microorganisms demonstrated that the AAA dressing was significantly more effective at killing pathogens than two other standard silver-containing dressings. Staining of bioburden extracellular components showed that the AAA dressing was also significantly more effective at reducing this adherent and protective component than standard silver-containing dressings. By combining disruptive and antimicrobial technologies in a dressing, it has been demonstrated using in vitro models that persistent bioburden can be disrupted and killed.

Conclusion: This in vitro study improves our understanding of how enhanced antimicrobial dressing technology may be effective against the challenge of persistent wound bioburden, and subsequently have a role in facilitating wound healing in the clinic.