Toxicity and Antimicrobial Activity of a Hydrocolloid Dressing Containing Silver Particles in an ex vivo Model of Cutaneous Infection

Abstract

In the present study we examined the effects of two hydrocolloid wound dressings (conventional silver-free Comfeel^®, silver-incorporating Contreet-H^®) on uninfected and Candida albicans- ormethicillin-resistant Staphylococcus aureus-infected reconstituted human epithelium (RHE). The morphological alterations of the keratinocytes caused by infection and by treatment were analysed with light and electron microscopy. As a measure of epithelial cell damage the release of lactate dehydrogenase from epithelial cells into the surrounding medium was monitored. Application of Contreet-H or Comfeel to uninfected RHE induced no major morphological effects on epithelial cells. Both wound dressings reduced the growth of micro-organisms. Specific alterations of the infected epithelium (vacuoles, spongiosis, oedema, detachment of keratinocytes) and invasion of the epithelium were significantly reduced only by treatment with Contreet-H. At the ultrastructural level release of silver by Contreet-H and superior antimicrobial efficacy could be verified. In summary, treatment with both wound dressings reduced the number of pathogens, with the silver-based wound dressing providing a more effective antimicrobial activity. This resulted in a strong decrease of pathogen-specific alterations of the infected epithelium. We present evidence that delivering silver to infected keratinocytes in a moist healing environment improves the benefit/risk ratio as compared to silver-free wound dressings.