Extended use of silver dressings: an in vitro study of efficacy

Dr Andrew May1, Dr Zlatko Kopecki1, Dr Bernard Carney2, Prof Allison Cowin1

1Future Industries Institute, University of South Australia, Adelaide, Australia, 2Women’s and Children’s Hospital, Adelaide, Australia

Abstract:

Background and aims: Large wounds including major burn injuries are highly susceptible to biofilm formation and microbial infections.1 Consequences of infected wounds include both mortality and significant morbidity. Antimicrobial dressings containing silver are widely used,2 but are expensive and current products are single use only, which is less cost effective. This study aimed to investigate the effectiveness of antimicrobial silver dressings that are opened and used in piecemeal fashion over three months.
Method: silver-based dressings were tested in vitro against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The standard Kirby-Brauer diffusion disc lab assay was used, which measures the zone of inhibition surrounding antimicrobial agents on agar plates. Antimicrobial efficacy of fresh dressings was tested before dressings were divided and stored at 4, 25 and 37 degrees. Dressings were subsequently sampled and efficacy tested at 1, 2, 3, 6, 8, 10 and 12 weeks. Dressings were also swabbed at each time point and cultured for microbial contamination.
Results: Aquacel Ag®, Acticoat® and Acticoat 7® were all effective against the tested pathogens with no loss of antimicrobial activity observed at any storage temperature. Mepilex Ag® showed no zone of inhibition against any pathogen. There was no growth from any dressing swab culture over the course of the study.
Conclusion: Silver dressings are likely to be safe and effective to use for up to 3 months, which could significantly impact costs of patient wound managment.

1. Aramwit, P. et al. (2010). In vitro evaluation of the antimicrobial effectiveness and moisture binding properties of wound dressings. Int J Mol Sci 11(8): 2864-2874.
2. Castellano, J. J. et al. (2007). Comparative evaluation of silver-containing antimicrobial dressings and drugs. Int Wound J 4(2): 114-122.


Biography:

Pre SET plastic surgery registrar with an interest in wound healing and equitable distribution of public funds.

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