Cath Lab Digest

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Index: Ostomy Wound Manage. 2012;58(1):16–22

Abstract
  Preclinical studies have shown that release of silver by different wound dressings varies. The purpose of this in vitro study was to compare the antimicrobial activity of silver alginate (SA) and silver carboxymethylcellulose (SCM) dressings. Antimicrobial activity was tested using nine bacterial strains with log10 reduction and corrected zone of inhibition (CZOI) assays. Antimicrobial effect was visualized using confocal microscopy (CLSM). Log₁₀ reduction was comparable between both dressings for Staphylococcus aureus NCIMB 9518, Candida albicans ATCC 90028, Finegoldia magna NCTC 11804^T, and Pseudomonas aeruginosa NCTC 10662. Log₁₀ reduction was higher for SCM than SA dressing-exposed Escherichia coli (P = 0.035) and P. aeruginosa ATCC 15692 (P = 0.032), and lower for SCM than SA dressing-exposed Streptococcus pyogenes (P = 0.007), Peptoniphilus asaccharolyticus (P = 0.045), and S. aureus NCTC 8325 (P = 0.012). Both dressings were equivalent against four strains (5 to 8 days’ activity) in the CZOI assay. SA dressing silver activity lasted >24 hours longer than SCM activity when exposed to C. albicans (9 days’ activity), E. coli (7 days’ activity), F. magna (5 days’ activity), and P. asaccharolyticus (5 days’ activity), whereas the SMC exhibited greater persistence against S. pyogenes (13 days’ activity). CLSM showed complete kill of S. aureus after 20 hours for both dressings. The results of this study confirm the broad-spectrum, in vitro activity of some dressings containing ionic silver. The in vitro antimicrobial efficacy of both wound dressings was comparable, but clinical studies comparing the efficacy and effectiveness of silver-containing dressings to nonionic silver-containing dressings are needed.

Keywords: in vitro study, wound dressings, micro-organisms, silver, alginate, carboxymethylcellulose

Potential Conflicts of Interest: This research was funded by a Knowledge Transfer Partnership Award and Dr. Hooper was the KTP associate. KTP funding had been awarded jointly to Advanced Medical Solutions Ltd, Winsford, Cheshire, UK and Cardiff University (Dr. Williams, Prof. Thomas, and Dr. Hill). Dr. Percival was Director of Research and Innovation, Advanced Medical Solutions, Winsford, UK.

Introduction

  Chronic wounds affect a high percentage of the worldwide population and their prevalence is increasing. Underlying medical conditions such as obesity and diabetes can induce chronic wound formation and subsequent delayed healing. These wounds generally are thought to exist in a state of continuous inflammation,¹ causing them to be considered out of balance, typified by prevention or delay of a proper wound healing response.

  Micro-organisms within wounds are known to affect wound balance.