(WHS-P59) ANTIMICROBIAL AND ANTIBIOFILM PERFORMANCE OF AN ULTRATHIN SYNTHETIC MATRIX CONTAINING SILVER AND GALLIUM
Friday, May 17, 2024
7:30 AM – 5:00 PM East Coast USA Time
Introduction: Biofilms are implicated in delayed healing in chronic wounds, however there is no commercially available topical formulation effective in dispersal of biofilms in wounds. Here we report the evaluation of antimicrobial, antimicrobial barrier and antibiofilm performance of a synthetic matrix, made of polyvinyl alcohol with a polymeric multilayer coating impregnated with silver and gallium, both in vitro and in vivo.
Methods: Antimicrobial performance of the matrix over 24 and 72 h was tested against 8 clinically relevant microbes (K. pneumoniae, E. coli, C. albicans, C. tropicalis, MRSA, S. aureus, P. aeruginosa, and E. faecalis) per ISO 22196. Its antimicrobial barrier performance was evaluated by pipetting 10 µL of bacterial inoculum of P. aeruginosa, A. baumannii or K. pneumoniae on the matrix placed on an agar plate and incubating at 37 ± 2 °C for 3 days and quantifying the CFU subsequently. To evaluate the antibiofilm performance in vitro, robust biofilms containing 108 CFU of A. baumannii or K. pneumoniae were established on gauze specimens over 48 h and rinsed with saline to remove planktonic bacteria. Moist biofilm specimens were then treated with a single application the matrix for 24 h, and the CFUs were determined relative to no-treatment controls. In vivo assessment was performed by transplanting preestablished biofilm in 1 cm dia. full thickness porcine wounds by placing the gauze specimens supporting 108 CFU P. aeruginosa biofilms for 24 h. Afterwards, the gauze specimens were removed and wounds were treated with the matrix once daily for two days. On day 3, biopsies of all wounds were minced and CFUs were determined relative to no-treatment control. All assays were carried out with at least three replicates for each sample. Groups were compared using a Student’s t test at P < 0.05.
Results: The matrix killed > 4 Log10 CFUs of all microbes tested per ISO 22196, thus confirming its antimicrobial activity against planktonic bacteria. It also killed bacteria on its surface and prevented the breakthrough of microbes over 72 h thereby demonstrating its ability to serve as an antimicrobial barrier. > 4 and 1.5 Log10 CFU reduction of A. baumannii and K. pneumoniae biofilms bacteria was achieved in vitro over 24 h with a single application of the matrix, and the matrix was killed 1.5 Log10 CFU of P. aeruginosa biofilm bacteria in vivo, thus establishing its antibiofilm performance.
Conclusion: The silver/gallium matrix is effective in killing both planktonic and biofilm bacteria and is thus suitable for assessment in the treatment of biofilms in chronic wounds.