Practical extended use of antimicrobial silver (PExUS)

Background: Antimicrobial silver has had a role in wound antisepsis throughout history and, with the rise in acquired antibiotic resistance, silver dressings are once again commonly used. Issues with silver dressings include the important environmental consideration of nanoparticle manufacture, and the significant financial cost of these products. One solution to these problems may be to adopt an opened-but-unused model of wound care whereby dressing materials are used in piecemeal fashion and excess stored in between dressing changes. Due to a lack of literature on the topic, this project was designed with the aim of testing the antimicrobial efficacy of available silver dressings during storage after opening.

Methods: Four commonly used silver dressings were tested for antimicrobial activity using a zone of inhibition assay against clinically important pathogens. The assay was performed on opening of dressings and repeated over 3 months in storage at 4, 25 or 37°C. Analysis was performed using repeated measures ANOVA. Swab cultures were taken at each simulated dressing change to detect microbial contamination of the dressings during storage.

Results: There was no effect of time or storage temperature on the zone of inhibition over the 12 week test period. No swabs taken returned culture consistent with microbial contamination of stored dressings.

Conclusion: Opened silver dressings maintain antimicrobial activity for at least 12 weeks in storage and are resistant to contamination. An opened-but-unused model for wound care is likely to improve cost-effectiveness while preserving effectiveness and safety.