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Lab Research
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The importance of test methodology when evaluating the efficacy of silver containing antimicrobial water-absorbing dressings First Author: Lawrence Korona Authors: Lawrence Korona The evaluation of antimicrobial properties of silver containing dressings is one of the key steps in the development process of new products. However, unlike safety and effectiveness testing, such as biocompatibility, no standards exist that are universally accepted for such an assessment. Antimicrobial dressings are marketed demonstrating efficacy using only references to zone of inhibition (ZOI) data. In the case of water absorbing devices, results from ZOI testing are influenced by the hydrodynamics of the dressing matrix interacting with the growth media. In addition the diffusion pathway of the silver ion is affected by the structure/chemistry of the dressing matrix, all of which is typically not accounted for in most testing methods. ZOI data on several different silver containing antimicrobial water-absorbing dressings (both foam and hydrocolloid based) were evaluated using different growth medias, and levels of hydration were gathered. Results indicate that vastly different apparent antimicrobial efficacy was found depending on type of media used, and degree of pre-test hydration. The case example is silver containing foam dressing that was reported to have a high ZOI was found to have no ZOI when a different media was used (TSA Vs Susceptibility Testing Agar). Thus is ZOI an appropriate test? |
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