64 A new antiseptic technique to mitigate bioburden in the skin.

Faculty Mentor: Dustin Williams (Orthopedics, University of Utah)

Introduction

The natural flora in human skin are common culprits in surgical site infection (SSI). The clinical standard to cleanse the skin prior to surgery follows administration of preoperative skin preparation (PSP) kits which commonly use antiseptic agents of Chlorhexidine gluconate (CHG) and Povidone-iodine (PVP-I). Previously, we have reported that CHG and PVP-I PSPs do not eradicate flora dwelling in the deepest dermal regions. In this study, we used an antiseptic-loaded dressing using three drugs in conjunction with PSP to test for bioburden reduction. Specific agents were chosen because of their relativity to healthcare products on the market: CHG Tegaderm, Ioban, and the Biopatch. We hypothesized that the drug reservoir would increase dermal absorption of antiseptic and decrease bioburden in a porcine model with Drug 3 having the greatest reduction.

Methods

Custom dressings were loaded using Drug 1, 2, and 3. The dorsum of the animal was clipped free of hair and cleansed with sterile water and Isopropyl alcohol. These prepared dressings were cleanly placed on the backs of 4 pigs. Several reference areas were also noted. The control area was not scrubbed with PSP nor had a dressing, the “no dressing” area was scrubbed without the placement of a dressing, and the “blank dressing” was placed on the animal without antiseptic to further understand properties of the model. After a 48 hour time point, the dressings were removed from the pig back. This tissue was then excised in 4x4cm pieces down to the fascia pigs following alternating scrubs of 4% CHG and alcohol and placed in a neutralizing media. The samples were blended, vortexed, sonicated, and then quantified. Identical samples were taken on control skin as a relative baseline (n=4/pig).

Results

With 3 treatment and reference groups, 24 samples were taken from each pig for a total of 96 samples. Bioburden was the lowest with applications of Drug 1 substantiating an average log reduction of 2.30 +/- 1.37, with Drug 2 – 2.50 +/- 1.03 and Drug 3 – 2.95 +/- 1.26 CFU/cm² following respectively. The reference groups provided comparative baselines. The control area was hypothesized to have the highest bioburden count, and was followed with an average log reduction of 4.70 +/- 0.488 CFU/cm². The blank dressing and no dressing areas displayed a greater log reduction of 2.83 +/- 1.20 and 2.83 +/- 1.20 CFU/cm², respectively.

Discussion

We hypothesized that Drug 3 would be more effective at suppressing bioburden when excising full thickness samples. Drug 3 did not perform as well as CHG and PVP-I when compared to the reference areas. Overall, Drug 1 eradicated the most bacteria present. The preloaded antiseptic reservoirs outweighed the control but had similar results to that of the “no dressing” and “blank dressing”. Due to these similarities, custom dressings propose further research to consider the effectiveness of clinical PSPs and current medical dressings. This research is fundamental for the development of a new PSP technology that eradicates deep dwelling microflora and mitigates SSI.