NEGATIVE PRESSURE WOUND THERAPY IN A CONTAMINATED MUSCULOSKELETAL WOUND MODEL: IS NPWT EFFECTIVE ON S. AUREUS?

Abstract

Purpose: Previous work demonstrated that negative pressure wound therapy (NPWT) resulted in less Pseudomonas aeruginosa than standard wet-to-dry (WTD) dressings in a complex orthopaedic wound model. Staphylococcus aureus is more clinically relevant in open fractures, and is the most prevalent bacteria in osteomyelitis. The purpose of this study is to determine if S. aureus responds similarly to P. aeruginosa when treated with NPWT.

Methods: A complex musculoskeletal wound was created on the hindlimb of 20 goats and contaminated with S. aureus (lux) bacteria. The bacteria are genetically engineered to emit photons, allowing for quantification with a photon-counting camera system. The wounds were débrided and irrigated with 9 L of normal saline using gravity flow irrigation 6 hours after inoculation. Goats were assigned to two different treatment groups: a control group using WTD dressing changes and an experimental group using NPWT. The wounds were débrided and irrigated every other day for 6 days. Bacteria within the wounds were quantified both before and after each débridement.

Results: There was no difference between treatment groups in amounts of bacteria in the wound at all time points (p≥0.37).

Conclusion: Previous work demonstrated that NPWT resulted in a significant and clinically relevant reduction of P. aeruginosa at all time points in a similar model. We presume that NPWT was effective because it created an environment that allowed the body to ward off this “opportunistic” gram negative. However, as shown in this study, S. aureus is less affected by NPWT and persists within the wound.