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 7-day randomised controlled pre-clinical trial utilising an existing extremity war wound model compared the efficacy of saline soaked gauze to commercially available dressings. The Flexor Carpi Ulnaris of anaesthetised rabbits was exposed to high-energy trauma using a computer-controlled jig and inoculated with 10⁶Staphylococcus aureus 3 hours prior to application of dressing. Quantitative microbiological assessment demonstrated reduced bacterial counts in INADINE (Iodine) and ACTICOAT (Nanocrystalline Silver) groups and an increase in ACTIVON TULLE (Manuka Honey) group (2-way ANOVA p<0.05).

Clinical observations were made throughout the study. Haematology and plasma cytokines were analysed at intervals. Post-mortem histopathology included 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 (SEM).

There were no bacteraemias, abscesses, purulent discharge or evidence of contralateral axillary lymph node activation. There were no significant differences in animal behaviour, weight change, maximum body temperature or white blood cell count elevation nor in pathology severity in muscle or lymph nodes (Kruskal-Wallis). There was no evidence of bacterial penetration or biofilm formation on SEM. Interleukin-4 and Tumour Necrosis Factor α levels were significantly higher in the ACTIVON TULLE group (1-way ANOVA p<0.05).

This time-limited study demonstrated a statistically significant reduction in Staphylococcus aureus counts in wounds dressed with INADINE and ACTICOAT and an increase in wounds dressed with ACTIVON TULLE. There was no evidence that any of these dressings cause harm but nor have we established any definite clinical advantage associated with the use of the dressings tested in this study.