Technology and product reviews T E C H N O L O G Y U P D A T E :


Evaluation of low-adherent antimicrobial dressings


Author: Michael Walker, Samantha


Jones, David Parsons, Rebecca Booth, Christine Cochrane, Philip Bowler


Through careful design of their physical characteristics, many modern wound dressings aim to provide a moist environment that is conducive to healing. Also, and perhaps equally as important, is the aim to ensure that there is minimal tissue trauma upon their removal. Several different approaches have been used to meet these design challenges, most notably the use of a low- tack or soft adhesive wound contact layer, such as those based on silicones, which claim to minimise wound adherence[1]


; and those based on materials


that gel on contact with exudate, for example, Hydrofiber® dressings, which have clinically been associated with reduced pain upon dressing removal[2, 3]


INTRODUCTION The terms ‘adherent’ and ‘adhesive’ are often inappropriately used as interchangeable descriptive words relating to dressing properties. Thomas[1]


.


Materials The silver-containing dressings and secondary adhesive cover dressing (ACD) used are listed in Table 1.


suggested that ‘adhesive’


should describe the interaction between the dressing and the peri-wound tissue, whereas ‘adherent’ describes the interaction of the dressing and the wound. While the former may be desirable, the latter should be avoided in a chronic wound. Dressing removal without causing tissue damage or pain to the patient is an important factor in helping to achieve the best possible clinical outcome within an appropriate protocol of care. In addition to low-adherence, a dressing may


References 1. Thomas E. Atraumatic dressings.


World Wide Wounds 2003. Available on line at: www.worldwidewounds. com/2003/january/thomas/ atraumatic-dressings.html


[accessed 18th November 2010].


2. Caruso DM, Foster KN, Hermans MHE, Rick C. AQUACEL® Ag in the management of partial-thickness burns: results of a clinical trial. J Burn Care Rehabil 2004; 25: 89–97.


3. Jurczak F, Dugre T, Johnstone A, Offori T, Vujovic Z, Hollander D. Randomised clinical trial of Hydrofiber dressing with silver


versus povidone-iodine gauze in the management of open surgical and traumatic wounds. Int Wound J 2007; 4: 66–76.


also be designed to reduce the risk of infection. This is most commonly achieved by the addition of an antimicrobial agent. A recent in vitro study on silver-containing dressings, including gelling fibre dressings and certain adhesive foam dressings, suggested that both dressing conformability and silver availability at the wound surface may be important in optimising the antimicrobial function of the dressing[4]


.


This paper presents further in vitro studies which investigate the challenges of combining low-adherence with antimicrobial protection in a modern wound dressing. This was undertaken by comparing commercially available examples of silver-containing gelling fibre dressings with certain silver-containing foam dressings that have an adhesive wound contact layer.


37 Wounds International Vol 2 | Issue 4 | ©Wounds International 2011


Bioadhesion studies Cell culture grade 6-well plates (Griener Ltd, UK); primary equine chronic wound fibroblasts isolated from tissue debrided during surgery; 0.5% Trypsin-EDTA solution; foetal calf serum (FCS) (Sigma, UK); Hank’s balanced salt solution (HBSS) (Invitrogen, UK), Neubauer counting chamber; a liquid growth medium comprised of: Dulbecco’s modified Eagle medium (DMEM), supplemented with 10% fetal calf serum, 20mm Hepes buffer, 100µg/ml penicillin/streptomycin and 0.5µg/ml amphotericin (Invitrogen Ltd, UK).


Microscopy Light microscope (Olympus SZ61) with QImaging camera (Device 3564); Image Pro Plus 7.0 image analysis software (MediaCybernetics, UK); a QUANTA 200 scanning electron microscope (SEM) (FEI Electron Optics, Holland) with Oxford INCA Energy Dispersive X-Ray Micro-Analysis (EDX) (Oxford Instruments, UK); K550X Sputter Coater (EMITECH, UK).


Seeded Agar Microbial Model Microbiological Media: pre-dried Tryptone Soy Agar Plates (TSA); molten Tryptone Soy Agar (TSA) (pre-cooled to ≈45ºC); Maximal Recovery Diluent (MRD); DE Neutralising Agar (DEA); Challenge organisms: Staphylococcus


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