Authors: Kiersten Gardner, Hannah Duffy, Abbey Blair, Nicholas Ashton, Porter Stulce, Dustin Williams
Mentors: Dustin Williams
Insitution: University of Utah
Transdermal antiseptic products as a method to decrease skin bioburden prior to surgery
Kiersten Gardner(1,2), Hannah Duffy(1,2), Abbey Blair(2), Nicholas Ashton(2), Porter Stulce1(2), Dustin Williams(1,2,3,4)
1 Department of Biomedical Engineering, University of Utah, Salt Lake City, UT
2 Department of Orthopaedics, University of Utah, Salt Lake City, UT
3 Department of Pathology, University of Utah, Salt Lake City, UT
4 Department of Physical Medicine and Rehabilitation, Uniformed Services University, Bethesda MD
Introduction:
Preoperative skin preparation (PSP) kits are used before surgery to prevent surgical site infection (SSI). These kits consist of alternating scrubs of alcohol and Chlorohexidine Gluconate (CHG) or Povidone Iodine (PVP-I). Transdermal antiseptic products like Ioban, Tegaderm, and Surgiclear are also used clinically to eradicate skin bacteria by releasing antiseptic over time. Despite these precautions, infections often occur, usually stemming from a patient’s endogenous skin flora. The bacteria causing SSI reside deep in dermal sweat glands and hair follicles, untouched by traditional PSP. To eliminate these bacteria, antiseptics must diffuse deeper into the skin at concentrations above the minimum inhibitory concentration (MIC). We screened FDA-approved topical antiseptic products using a modified Kirby Bauer Assay to assess bacterial kill over time. We hypothesized that extended use of topical antiseptic products prior to surgery would kill deep-dwelling skin bacteria. We tested the extended use of these products on pig backs in conjunction with a CHG PSP to evaluate remaining bioburden.
Methods:
We determined the minimum inhibitory concentrations (MIC) for CHG and PVP-I against three common skin bacterial strains. We then took 6 mm biopsy punches of Tegaderm, Surgiclear, and Ioban and placed them on fresh bacterial lawns daily for 3 days. We measured the zones of inhibition (ZOI). Lastly, we applied the products to the backs of 4 Yorkshire pigs (n=4 products per test). After 48 h, we removed the products, performed a PSP- CHG scrub, and excised skin sections underneath the products. We homogenized the skin and quantified colony forming units (CFU)/g tissue. We analyzed the outcomes statistically using a mixed effects linear regression to determine significance.
Results:
The average MIC values for CHG and PVP-I were 2 and 2,000 ug/mL for Staphylococcus aureus, respectively. The average 24 h ZOIs for S. aureus were 7.9, 22.4, and 10.1 mm for Ioban, Tegaderm, and Surgiclear, respectively. The average log10 reduction for the CHG PSP, Ioban, Tegaderm, and Sugiclear were 1.87 ± 0.232, 1.65 ± 0.192, 1.69 ± 0.222, and 1.77 ± 0.316 CFU/cm2, respectively. The p values between the CHG PSP and Ioban, Tegarderm, and Surgiclear were 0.491, 0.572, and 0.746, respectively.
Discussion:
The benchtop data indicated adequate antiseptic diffusion and kill. In the porcine model, however; the presence of any of the products resulted in a statistically insignificant log reduction. Extended use of FDA-approved transdermal antiseptic products does not appear to decrease the skin’s bioburden. It appears that the products are not releasing high enough concentrations of the antiseptic to kill bacteria.