Laboratory Research
Thermo-reversible property of the hydrogel was assessed using Brookfield viscometer during temperature increment and decrement. In vitro antimicrobial property against major chronic, burn and combat wound pathogens, Staphylococcus aureus, Methicillin resistant S. aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae was assessed using modified ASTM E235-03 method. Mature biofilm of these organisms grown on nitrocellulose membrane at 37°C for 72 h were treated with the thermo-reversible hydrogel (TRH) for 7 days and viable numbers were determined. A three-patient case study was conducted to assess effect of TRH application on bacterial colonization of foot and toe ulcers.
Results: Viscosity of TRH increased with temperature increment, reaching maximum of 17500 cP at 35°C and viscosity decreased with temperature decrement, reaching < 1000 cP at ≤17°C. TRH reduced viable numbers of tested organisms by ≥5 log CFU ≤30 min. Treatment with TRH reduced viable numbers of biofilms of all organisms by ≥4 log CFU at day 3 and no biofilm re-growth of these organisms was noted until day 7. In all three case studies, fluorescent imaging of foot and toe ulcers showed bacterial colonization. No bacterial colonization was detected by fluorescent imaging after a week of TRH use.
Discussion: At 35 ˚C, TRH was thick and non-runny gel. This property can help gel to remain on wound. As it was shown in temperature decrement, viscosity of the gel decreased, which would aid removing gel from wound at dressing change with cold water or saline without harming wound tissue. Activity against biofilms was sustaining and lasted for up to 7 days. Case studies provided real-life evidence that TRH can remove bacterial colonization from foot and toe ulcers and can facilitate wound healing/closure. This study provides a direct correlation of in vitro antimicrobial and antibiofilm effects of TRH with reduction of bacterial colonization on wounds.