Plastic Surgery Research Council
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IN VITRO EVALUATION OF P. AERUGINOSA DISRUPTION FROM HARDWARE MATERIALS USING NEGATIVE PRESSURE WOUND THERAPY WITH INSTILLATION (NPWTI) AND SELECT TOPICAL SOLUTIONS
Presenter: Chris Lessing, PhD
Co-Authors: Rycerz AM
KCI

When implanted medical hardware becomes contaminated with bacteria, surgical intervention can be required to treat the infection. Surgeons in the United States typically remove the hardware, treat the infection, and replace the hardware in a separate surgical procedure weeks later. However, a recent study in Europe showed potential benefits of using Negative Pressure Wound Therapy with Instillation (NPWTi) and surgical debridement to help salvage hardware in some patients (Lehner et al., Int Orthop 2011. 35(9) 1415-1420). Our in vitro study evaluated the susceptibility of Pseudomonas aeruginosa biofilms grown on medical implant materials exposed to NPWTi. ASTM Standard Method E2647-08 was adapted to grow P. aeruginosa biofilms on ultra high molecular weight polyethylene (UHMWPE) and type 316L stainless steel coupons. The biofilm-covered coupons were then treated with NPWTi for 24 hours at default settings (alternating 10 minute soak with topical solution followed by 3.5 hours NPWT at -125 mmHg) with one of the following topical solutions: 0.1% polyhexanide with 0.1% undecylenamidopropyl betaine, 0.125% sodium hypochlorite, or 0.9% sodium chloride (saline). Control coupons were covered with saline-soaked gauze during the same 24-hour period. Bacteria remaining after treatment were quantified (6 replicates per group). Biofilm growth controls were 7.4 log CFU/cm2 on stainless steel; these were reduced to 1.5 log CFU/cm2 with polyhexanide, 5.4 log CFU/cm2 with sodium hypochlorite, and 6.6 log CFU/cm2 with saline. Similarly, biofilm growth controls were 7.5 log CFU/cm2 on UHMWPE; these were reduced to 1.6 log CFU/cm2 with polyhexanide, 4.9 log CFU/cm2 with sodium hypochlorite, and 6.8 log CFU/cm2 with saline. The polyhexanide solution provided the greatest reduction in bacteria on both materials, with a nearly 6 log CFU reduction compared to controls. Sodium hypochlorite reduced bacteria by at least 2 log CFU on both materials, while saline had an effect of less than 1 log CFU. These in vitro data suggest that NPWTi with the appropriate topical wound treatment solutions may have an effect on P. aeruginosa biofilms.


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