Efficacy of a novel thermo-reversible wound gel against antibiotic tolerant biofilm

Chronic wounds are frequently colonized by biofilm-forming bacteria, and one of the defining characteristics of these infections is the resulting tolerance to antibiotics. A novel thermo-reversible antimicrobial wound gel (revyve ® Antimicrobial Wound Gel, TRG), formulated to target biofilms, was evaluated for its ability to inactivate antibiotic-tolerant biofilms using both a colony biofilm model and a porcine skin explant biofilm model. Mature biofilms of Staphylococcus aureus and Pseudomonas aeruginosa were grown on nitrocellulose membranes or porcine skin explants for 72 hours at 37 °C. Before any treatment, viable numbers of S. aureus and P. aeruginosa were ≥ 9.7 log CFU in the colony biofilm model, and 8.3 and 6.6 log CFU, respectively, in the porcine skin explant model. Biofilms were then washed and treated with defined concentrations of antibiotics for 24 hours to select for antibiotic-tolerant cells, followed by up to 7 days of TRG treatment. Antibiotic treatment caused a significant (P ≤ 0.05) reduction in viable numbers of both organisms in both models, resulting in survival of ≥ 5 log CFU of tolerant biofilm cells. Subsequent treatment with TRG reduced viable numbers of S. aureus to below detection limits, causing a 7.9 log CFU reduction at 24 hours in the colony biofilm model and a 5.5 log CFU reduction at 72 hours in the porcine skin explant model. In the colony biofilm model, viable numbers of P. aeruginosa were reduced to below the detection limit, corresponding to a 6.1 log CFU reduction at 24 hours, while in the porcine skin explant model, TRG caused a 3.5 log CFU reduction at 72 hours, with no further changes observed up to 7 days. These results indicate that TRG was effective at inactivating antibiotic-tolerant biofilms and may serve as a valuable tool in combating biofilms in chronic wounds.