Experimental evaluation of a modified polyurethane foam coating for local delivery of antimicrobial agents in burn wounds

Background . Treatment of deep infected burn wounds remains an urgent problem due to the risk of infectious complications and the need to create conditions for tissue repair. A promising approach is the use of wound coatings capable of maintaining a moist environment and serving as a matrix for the local delivery of antimicrobial agents. Objective . The aim of the study was to experimentally evaluate the course of reparative processes in infected burn wounds in rats using a modified polyurethane foam coating wetted with a bacteriophage solution or antiseptic without daily removal from the wound surface. Materials and methods . The study was performed on 14th Wistar rats. A grade III contact burn was simulated, followed by fascial necrectomy and wound contamination with MRSA Staphylococcus aureus clinical isolate. The animals were randomized into two groups: in group 1, a modified polyurethane foam coating with a bacteriophage solution was used, and in group 2— a coating with 0.01 % benzyldimethyl[3- (myristoylamino)propyl] ammonium chloride solution was used. The preparations were applied twice a day to the outer surface of the coating in a volume equal to ½ of its sorption capacity. The dynamics of changes in the wound area, the healing index, the macroscopic picture and histological changes were evaluated. Research results . In both groups, there was a marked decrease in the area of the wound defect. By the 14th day of treatment, the wound area in the bacteriophage group decreased from 686.12 ± 123.98 to 62.78 ± 26.10 mm 2 , in the antiseptic group — from 785.26 ± 102.37 to 49.71 ± 29.47 mm 2 . There were no statistically significant intergroup differences. The healing index on the 14th day was 11.28 ± 0.98 and 11.05 ± 2.98, respectively. Histologically, both groups showed closure of the defect with multilayer squamous epithelium, restoration of epidermal stratification, formation of connective tissue in the defect area, and minor inflammatory infiltration. Conclusion . The use of a modified polyurethane foam coating wetted with a solution of a bacteriophage or antiseptic was accompanied by a favorable course of reparative processes in the model of an infected burn wound. The dynamics of healing in the two variants of antimicrobial support was comparable. The proposed delivery scheme presumably helps to maintain a moist environment and creates the possibility of introducing an antimicrobial agent without daily coating removal.