A pre-clinical evaluation of silver, iodine and Manuka honey based dressings in a model of traumatic extremity wounds contaminated with Staphylococcus aureus

Abstract

Prevention of extremity war wound infection remains a clinical challenge. Staphylococcus aureus is the most common pathogen in delayed infection. We hypothesised that choice of wound dressings may affect bacterial burden over 7 days reflecting the current practice of delayed primary closure of wounds within this timeframe.A randomised controlled trial of 3 commercially available dressings (Inadine® (Johnson & Johnson, NJ, USA), Acticoat® (Smith & Nephew, Hull, UK), Activon Tulle (Advancis Medical, Nottingham, UK)) was conducted in a rabbit model of contaminated forelimb muscle injury. A positive control group treated with antibiotics was included. Groups were compared to a saline soaked gauze control. The primary outcome was a statistically significant reduction (p<0.05) in tissue S. aureus at 7 days post-injury. Secondary outcome measurements included bacteraemias, observational data, whole blood determination, ELISA for plasma biomarkers, PCR array analysis of wound healing gene expression and muscle/lymph node histopathology.Antibiotic, Inadine and Acticoat groups had statistically significant lower bacterial counts (mean 7.13 [95% CI 0.00–96.31]×102; 1.66 [0.94–2.58]×105; 8.86 [0.00–53.35]×104cfu/g, respectively) and Activon Tulle group had significantly higher counts (2.82 [0.98–5.61]×106cfu/g) than saline soaked gauze control (7.58 [1.65–17.83]×105cfu/g). There were no bacteraemias or significant differences in observational data or whole blood determination. There were no significant differences in muscle/loss or pathology and lymph node cross-sectional area or morphology. There were some significant differences between treatment groups in the plasma cytokines IL-4, TNFα and MCP-1 in comparison to the control. PCR array data demonstrated more general changes in gene expression in the muscle tissue from the Activon Tulle group than the Inadine or Acticoat dressings with a limited number of genes showing significantly altered expression compared to control.This study has demonstrated that both Acticoat® and Inadine® dressings can reduce the bacteria burden in a heavily contaminated soft tissue wound and so they may offer utility in the clinical setting particularly where surgical treatment is delayed.