Development and evaluation of silver-impregnated amniotic membrane as an antimicrobial burn dressing

Silver has been widely used as an antimicrobial agent in burn wound care. A number of dressings containing silver have been developed using textiles, polyurethane films, foams, hydrogels, and hydrocolloids. However, biological-derived wound dressings have been advocated for their ability to more effectively promote healing and regulation of evaporation and exudation at the wound site. An antimicrobial burn dressing was developed by impregnation of silver on the amniotic membrane. The dressing was assessed for antimicrobial effectiveness and physical properties of relevance to clinical performance. Silver-impregnated dressings exhibited antimicrobial activity in contact for 5 days. An in vitro evaluation of the microbicidal efficacy of the silver-impregnated dressing was performed using Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans with different contamination level. More than 95% reduction in viable counts was observed in 2 to 4 hours. The release of silver from the dressings was observed for up to 4 days. Moisture vapor transmission rate was 1037 +/- 38 g/m(2)/24 hr for silver-impregnated dressings and 1024 +/- 44 g/m(2)/24 hr for amniotic membrane. The fluid absorption by the silver-impregnated dressings was comparable to the amniotic membranes. The total fluid handling capacity of the silver-impregnated amniotic membrane dressing examined ranged from 4 to 6.6 g/10 cm(2) in 24 to 96 hours. The silver-impregnated amniotic membranes also provided an effective barrier to bacterial penetration. The study has demonstrated the ability of silver-impregnated amniotic membrane to combat microbial infection and its ideal physical characteristics for clinical use as a burn wound dressing.