Assessment of Zwitterionic Hydrogels for Antimicrobial Efficacy in a Controlled Porcine Burn Wound Infection Model

Abstract

Burn injuries impose significant healthcare and logistical burdens in both civilian and military settings. This includes infectious complications that are amplified in prolonged field care environments where surgical intervention is delayed. As such, there is a growing need for adjunctive therapies that mitigate infection and zwitterionic (ZW) hydrogels offer a promising solution for maintaining a moist wound environment and reducing bacterial colonization. This study evaluates the safety and efficacy of two ZW hydrogel products: CleraFlexTM and a ZW hydrogel loaded with polyhexamethylene biguanide (PHMB) in infected burns in swine under simulated prolonged field care conditions. Ten-5x5cm contact burns were created on the dorsum of Yorkshire-cross swine (n=3) and inoculated with Pseudomonas aeruginosa (ATCC #27853, 2.5 x 105 CFU). Wounds were treated with saline, triple antibiotic ointment (TAO), CleraFlex, or ZW + PHMB. Photographs and biopsies were obtained. On day 7 post-burn, wounds appeared infected due to greenish discoloration to varying degrees. Saline-treated wounds had the highest bacterial burden (9.38±0.40 log CFU/g). TAO treatment resulted in a non-significant reduction to 6.95±0.63 log CFU/g (p=0.078), whereas CleraFlex and ZW + PHMB achieved greater significant reductions (6.39±0.36 log CFU/g and 5.98±0.65 log CFU/g, respectively; (p<0.05 and p<0.01). Blinded histological analysis also showed reduced leukocyte extravasation, and potentiated removal of the necrotic eschar in burn wounds treated with ZW +/- PHMB. ZW formulations +/- PHMB significantly reduced bacterial burden in a porcine burn-infection model simulating prolonged field care, supporting their potential as effective adjuncts in managing infection during delayed evacuation in austere environments.