Evaluation of topical therapy with silver-kaolin (Argostop) in an experimental model of burn wound sepsis

Burn wound therapy with silver-kaolin, a topical agent applied as an aerosol spray, was evaluated in male rats given a 20 per cent total body surface area, full thickness dorsal scald burn. Burn wounds treated with silver-kaolin healed at rates comparable to untreated wounds. No significant differences were noted in the numbers or types of organisms colonizing the wounds of treated and untreated rats at 5, 12 and 19 days post-burn. To evaluate the effectiveness of silver-kaolin in treating burn wound sepsis, rats were inoculated on the wound surface with 2.5 x 10(8) Pseudomonas aeruginosa. This inoculum resulted in 100 per cent mortality in untreated rats. Rats treated with silver-kaolin had a mortality rate of 71 per cent, compared to a 9 per cent mortality rate in rats treated with 1 per cent silver sulphadiazine. When silver-kaolin was applied to the wound prior to bacterial inoculation, the mortality rate was reduced to 6 per cent. When wounds were treated with kaolin alone and then inoculated with bacteria, the mortality rate was 50 per cent, indicating that part of the effectiveness of silver-kaolin appeared to be due to a barrier effect. These results indicate that silver-kaolin may be useful for preventive topical antimicrobial therapy of acute burns or after wound debridement or excision, but is not suitable for therapy of wounds previously colonized by microorganisms.