Technology update Evaluation of low-adherent antimicrobial dressings
Dry
20 40 60 80
Figure 1– Simulated bioadhesion of dry and pre-hydrated silver-containing dressings. 0
80 60 40 20 0
HF-Ag AL-Ag Foam A
aureus (NCIMB 9518) and Pseudomonas aeruginosa (NCIMB 8626).
METHODS Simulated bioadhesion studies These studies used a quantitative in vitro model that was developed for the measurement of cellular adhesion to wound dressings[5]
. Briefly,
equine fibroblasts were harvested from stock dishes, and plated out at 2x105 cells per well in six-well cell culture grade plates. The plates were incubated at 37o
C for 24 hours to allow
the cells to attach to the dish. Test dressings were cut into 1cm2
pieces and either applied
dry or pre-hydrated in isotonic saline solution, placed firmly but carefully onto the surface of the cell layer and incubated for a further 24 hours. After incubation, the test dressings
Foam B Foam C
Hydrated
were carefully removed to avoid cell damage or disruption and washed with HBSS to remove any non-adherent cells. After washing, trypsin- EDTA was applied to the dressings to release adhered cells and the reaction was stopped by adding DMEM with FCS. The released cells were centrifuged at 1400rpm for four minutes and the supernatant was discarded. The cell pellets were re-suspended in DMEM, the number of released cells was determined manually using a Neubauer counting chamber, and the number of cells that had adhered to each dressing was calculated. This experiment was repeated six times for each test dressing both in the dry and pre-hydrated states.
References
Microscopy Topographical features of the wound contact surface of each dressing were studied using a
4. Bowler P, Jones S, Towers V, Booth R, Parsons D, Walker M. Dressing conformability and silver-containing wound dressings. Wounds UK 2010; 6: 14–20.
Silver-containing dressings HF-Ag (AQUACEL® AL-Ag (SILVERCEL™
Management)* Foam A (Mepilex™ Foam B (Allevyn™
Ag, ConvaTec)* Non-adherent, Systagenix Wound Ag, Mölnlycke Healthcare) Ag Gentle, Smith and Nephew)
Foam C (Allevyn™ Ag Gentle Border, Smith and Nephew)
XC®
Dressing type Hydrofiber®
dressing with 1.2% w/w ionic silver*
Non-adherent Hydro-Alginate dressing containing silver- coated nylon fibres
Silicone adhesive foam containing silver sulphate Soft gel adhesive foam containing silver sulfadiazine Silicone gel adhesive foam containing silver sulfadiazine
*Note: these dressings were covered with the adhesive cover dressing (ACD) (Versiva®
Adhesive (10x10cm), an adhesive gelling foam dressing with Hydrofiber® Technology: ConvaTec)
5. Cochrane C, Rippon MG, Rogers A, Walmsley R, Knottenbelt D, Bowler P. Application of an in vitro model to evaluate bioadhesion of fibroblasts and epithelial cells to two different dressings. Biomaterials 1999; 20: 1237–44.
6. Hoeskstra MJ, Hermans MHE, Richters CD, Dutrieux RP. A histological comparison of acute inflammatory responses with a Hydrofiber or tulle gauze dressing. J Wound Care 2002; 11(2): 113–19.
Table 1 – Materials used in the studies.
7. Moffatt CJ, Franks PJ, Hollinworth H. Understanding wound pain and trauma: an international perspective In: European Wound Management Association (EWMA). Position Document. Pain at wound dressing changes. 2002; London: MEP Ltd: 2–7.
www.woundsinternational.com
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Technology and product reviews
Cell counts (x 1000)
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