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Laboratory Research
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The importance of bacterial strains and kill rate in evaluating the efficacy of silver antimicrobial wound dressings David Brett, BS, BS, MS, Smith & Nephew, Largo, FL There are currently many silver based antimicrobial dressings available to the clinician. In reviewing the literature and spending time with clinicians, there seem to be specific areas of confusion. Two of these areas, Òstrains of pathogensÓ and Òrate of killÓ will be addressed here. The purpose of this study is to investigate these areas in hopes of clearing up some of the confusion around silver. Some of the published data indicates that very low levels of active silver achieve bactericidal activity; however, this view is in contrast to other data sources and much of the peer reviewed literature. So, how can this disconnect be explained? It is key to understand that all pathogens have multiple strains and different strains require different levels of silver for kill, thus some strains can be killed with very low levels of silver. Other strains require significantly higher levels of silver for kill. In this study a variety of silver dressings are evaluated (log reduction) against 5 different strains of P. aeruginosa (cultivated from wounds). Silver technologies with the ability to provide their maximum level of active silver quickly and then maintain that level for a prolonged period of time were the most efficacious in this study. As the clinician is not likely to know which strain of pathogen (or the number of different strains) and at times, which pathogens are present in a wound, a technology with these properties will likely be of value in managing bioburden. Ovington LG. The Truth about Silver. Ostomy Wound Manage. 2004;50;(9A suppl):1SÐ10S Parsons D, Bowler PG, Myles V, Jones S. Silver Antimicrobial Dressings in Wound Management: A Comparison of Antibacterial, Physical & Chemical Characteristics. WOUNDS. 2005;17(8):222Ð232. |
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