Evaluation of an In-vivo Efficacy of Various Concentrations of PVP/NO-based Formulations on Infected Wounds with Pseudomonas Aeruginosa ATCC 27312 and Healing Process Using a Superficial Partial Thickness Porcine Wound Model

Background: Nitric Oxide (NO)-based products are known to have antimicrobial and antibiofilm properties.

Purpose: The goal of this study was to determine the effects of various NO-releasing polyvinylpyrrolidone (PVP/NO) based formulations in reducing Pseudomonas aeruginosa and enhancing healing in a porcine deep partial thickness wound model. 

Methods: Deep partial thickness wounds were created on the back of three pigs. Two animals were used for microbiology analysis and the wounds were inoculated with Pseudomonas aeruginosa ATCC 27312 (PA). One animal's wounds were treated within 20 minutes (biofilm prevention) and others were treated after 24 hr biofilm formation (biofilm elimination). For the wound healing assessment, one animal had wounds created (non-inoculated) and treated within 20 minutes (histology assessments). Wounds were randomly assigned to one of five treatment groups: 1) 1% PVP/NO, 2) 5% PVP/NO, 3) Vehicle Control, 4) Untreated Control (Tegaderm) and 5) silver sulfadiazine (SSD). Wounds were assessed on days 3 and 6 (microbiology) and on days 2, 4 and 6 (histology). For the wound healing study, treatments 1-4 were evaluated by histology.

Results: In the biofilm elimination study, three baseline wounds were recovered before treatment. The biofilm elimination results showed that PVP/NO (1 and 5%) were able to reduce PA throughout the study, with a reduction on day 6 of at least 94.83% when compared against untreated control or baseline wounds. Biofilm prevention results show 5% PVP/NO formulation on day 3 reducing the bioburden comparable to the efficacy of the positive control SSD. This group had bacterial reduction of 99.50% compared to Untreated Control. On day 6, wounds treated with PVP/NO (5%) resulted in less bacterial count compared with PVP/NO (1%). None of the treatments groups in the wound healing study were detrimental and reached 100% of epithelialization on day 6.

Conclusion: Data suggest that 1% PVP/NO and 5% PVP/NO treatments are beneficial for controlling infection and enhancing the healing at the same time. Additional studies are needed to obtain statistical analysis and substantiate these findings.