A randomised controlled trial was conducted using a rabbit model of a complex contaminated extremity war wound. Compared to saline soaked gauze dressings Inadine (iodine) and Acticoat (nanocrystalline silver) had significantly lower levels of Staphylococcus aureus after 7 days while Activon Tulle (Manuka honey) had significantly higher levels. Molecular level analysis of the wound was conducted. Plasma cytokines of interest were assayed using ELISA and levels of expression of relevant tissue genes measured using PCR following RNA extraction. Appreciable levels of Interleukins 4 and 6 and Tumour Necrosis Factor-α were identified in plasma with significantly higher levels of IL-4 and TNFα detected in the Activon Tulle group. In tissue TNFα, Matrix metalloproteinase-3 and the ratio of Matrix metalloproteinase-9 to Tissue Inhibitor of Matrix metalloproteinase-1 were significantly higher in tissue injured limbs than the uninjured limbs with no significant differences between groups. Interpretation of these results is challenging. IL-4 has been associated with transition from pathological inflammation to repair and TNFα with impaired healing. However, Activon Tulle had significantly higher levels of S. aureus and we found no differences in observational, histology, haematology or tissue gene expression outcomes over 7 days which would correlate with these molecular biology results

A randomised controlled pre-clinical trial utilising an existing extremity war wound model compared the efficacy of saline soaked gauze to commercial dressings. The Flexor Carpi Ulnaris of anaesthetised New Zealand rabbits was exposed to high-energy trauma using computer-controlled jig and inoculated with 10. 6. Staphylococcus aureus 3 hours prior to application of dressing. After 7 days the animals were culled. Quantitative microbiological assessment of post-mortem specimens demonstrated statistically significantly reduced S aureus counts in groups treated with iodine or silver based dressings (2-way ANOVA p< 0.05). Clinical observations and haematology were performed during the study. Histopathological assessment of post-mortem muscle specimens included image analysis of digitally scanned haematoxylin and eosin stained tissue sections and subjective semi-quantitative assessment of pathology severity using light microscopy to grade muscle injury and lymph node activation. Tissue samples were also examined using scanning electron microscopy to determine the presence of bacteria and biofilm formation within the injured muscle. Non-parametric data were compared using Kruskal-Wallis. There were no bacteraemias, significantly raised white cell counts, abscesses, purulent discharge or evidence of contralateral axillary lymph node activation. All injured muscle specimens showed evidence of haemorrhage, inflammatory cell infiltration and fibrosis. All ipsilateral axillary lymph nodes were activated. There were no significant differences in the amount of muscle loss, size of the activated lymph nodes or in subjective semi-quantitative scoring criteria for muscle injury or lymph node activation. There was no evidence of bacterial penetration or biofilm formation. This study demonstrated statistically significant reductions in Staphylococcus aureus counts associated with iodine and silver dressings, and no evidence that these dressings cause harm. This was a time-limited study which was primarily powered to detect reduction in bacterial counts; however, there was no significant variation in secondary outcome measures of local or systemic infection over 7 days