Sterilization of Medical Dressings with Enhanced Antimicrobial Properties

Abstract

The present invention relates to a sponge dressing for treating wounds comprised of a polymer sponge containing a plurality of antimicrobial dyes with at least one dye being gram positive and at least one other dye being gram negative and a silicon adhesive secured to a sponge surface. The sponge dressing can be exposed initially to gamma radiation and later sterilized by ethylene oxide or alternatively it can be sterilized by ethylene oxide and later irradiated by gamma radiation. The sponge dressing has a morphology characterized by an average pore throat diameter of 0.5-500 μm and a porosity ranging from about 60% to about 99.5%. The sponge dressing can also contain at least one biofilm reducing agent, at least one chelating agent and an ionic and non-ionic surfactant.

What is claimed is: 
     
         1 . A sterile dressing for treating wounds comprised of a polymer sponge containing a plurality of antimicrobial dyes with at least one dye being gram positive and at least one other dye being gram negative said dressing being exposed to both gamma radiation and ethylene oxide, and a silicon adhesive secured to said sponge surface. 
     
     
         2 . The sterile dressing of  claim 1  wherein said dyes are taken from a group of dyes consisting of triaryl or diarylmethanes, methylene blue, toluidine blue, methylene violet, azure A, azure B, azure C, brilliant cresol blue, thionin, methylene green, bromcresol green, crystal violet, acridine orange, brilliant green, acridine yellow, quinacrine, trypan blue, trypan red and mixtures of these dyes. 
     
     
         3 . The sterile dressing of  claim 1  wherein said sponge is taken from a group of polymers consisting of polyvinyl formal, polyvinyl acetal, polyurethane, polyester, or a mixture of polymers. 
     
     
         4 . The sterile dressing of  claim 1  wherein said gram positive and gram negative dyes are methylene blue and crystal violet respectively. 
     
     
         5 . The sterile dressing of  claim 1  wherein said sponge has a morphology characterized by an average pore throat diameter of 0.5-500 μm, a fluid retention of 5.5-25.0 mL fluids/g porous material, a density of 0.05-0.15 g polymer/cm 3  porous material, and a porosity of 60% to 99.5%. 
     
     
         6 . The sterile dressing of  claim 1  wherein said dressing has a cell structure which is open and interconnected by pores suitable to provide capillary flow porosity and liquid extrusion porosimetry. 
     
     
         7 . The sterile dressing of  claim 1  wherein said sponge contains biofilm reducing agents taken from a group consisting of amylase enzymes (e.g. amyloglucosidase, bacterial amylo novo), protease enzymes (e.g. savinase and everlase) fibrinolytic agents (e.g. plasmin, streptokinase, and nattokinase, and TrypLE), deoxyribonuclease I, glycoside hydrolase dispersin B, and cellulase. 
     
     
         8 . The sterile dressing of  claim 1  wherein said sponge contains chelating agents to sequester the metals that crosslink polysaccharides in the biofilm taken from a group consisting of ethylenediaminetetraacetic acid (EDTA), citrates, phosphonates and phosphonic acids. 
     
     
         9 . The sterile dressing of  claim 1  wherein said sponge contains an ionic and non-ionic surfactant which are used to stabilize biofilm macromolecules. 
     
     
         10 . The sterile dressing of  claim 9  wherein said ionic surfactants are taken form a group consisting of zwitterionic, and include alkyl sulfates (e.g. sodium dodecyl sulfate), alkyl carboxylates, (e.g. sodium stearate), tertiary or quarternary alkyl ammoniums (e.g. cetrimonium bromide, cetrimonium chloride, cetrimonium stearate), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). 
     
     
         11 . The sterile dressing of  claim 1  wherein said polymer sponge is polyurethane. 
     
     
         12 . The sterile dressing of  claim 1  wherein said polymer sponge is polyvinyl acetal. 
     
     
         13 . A sterile dressing for treating wounds comprised of a polymer sponge containing a plurality of antimicrobial dyes with at least one dye being gram positive and at least one other dye being gram negative and a silicon adhesive secured to a sponge surface, said dressing being exposed to gamma radiation until it absorbs from about 5 to about 36 kilogray of radiation and sterilized by ethylene oxide; said dyes are methylene blue and gentian violate, said sponge having a morphology characterized by an average pore throat diameter of 0.5-500 μm and a porosity ranging from about 60% to about 99.5% and also containing at least one biofilm reducing agent, at least one chelating agent and an ionic and non-ionic surfactant. 
     
     
         14 . The sterile dressing of  claim 13  wherein said sponge contains biofilm reducing agents taken from a group consisting of amylase enzymes (e.g. amyloglucosidase, bacterial amylo novo), protease enzymes (e.g. savinase and everlase) fibrinolytic agents (e.g. plasmin, streptokinase, and nattokinase, and TrypLE), deoxyribonuclease I, glycoside hydrolase dispersin B, and cellulase. 
     
     
         15 . The sterile dressing of  claim 13  wherein said sponge contains chelating agents to sequester the metals that crosslink polysaccharides in the biofilm taken from a group consisting of ethylenediaminetetraacetic acid (EDTA), citrates, phosphonates and phosphonic acids. 
     
     
         16 . A process of sterilizing a dyed polymer sponge dressing wherein said dyes are antimicrobial comprising the steps of:
 a) dying a sponge dressing with antimicrobial dyes,   b) exposing the dyed sponge dressing to gamma radiation for a period suitable to apply gamma radiation ranging from about 5 to about 36 kilogray to said sponge dressing; and   c) treating the radiated sponge with an EO sterilization.   
     
     
         17 . A process of sterilizing a dyed sponge dressing wherein said dyes are antimicrobial comprising the steps of:
 a) dying a sponge with gram positive and gram negative dyes;   b) exposing the dyed sponge to gamma radiation; and   c) treating the radiated sponge with an EO sterilization having a cycle temperature of about 108° F., a cycle humidity of about 30% RH and an EO sterilant concentration of about 600 mg/L.   
     
     
         18 . The process of  claim 17  wherein said sponge dressing is a foamed polymer. 
     
     
         19 . A sterile dressing for treating wounds comprising a polymer dressing containing at least one antimicrobial dye and a silicon adhesive secured to a dressing surface, said dressing being sterilized by both ethylene oxide and gamma radiation. 
     
     
         20 . The dressing of  claim 19  wherein said polymer dressing is taken from a group of polymers consisting of polyvinyl formal, polyvinyl acetal, polyurethane, and a mixture of said polymers.