Use of a noncontact radiant heat bandage and Staphylococcus aureus dermal infections in an ovine model

Diabetic foot wounds are difficult to manage due to relative tissue ischemia and high rates of soft tissue infection. One potential treatment modality is the application of local radiant heat to promote wound healing and control infection. However, there are concerns that local heat will spread rather than control infection. We determined in this study the effect of a noncontact radiant heat bandage in controlling an ischemic soft tissue infection. Bilateral 10 × 15 cm dermal flaps were created in 15 adult range sheep. The flaps were inoculated intradermally with 10⁷ Staphylococcus aureus in 3 separate areas. The control flap was left open to air, while the treatment flap was covered with a noncontact radiant heat bandage and heated to 38°C for three 1-hour periods separated by two 1-hour nonheating periods daily. After 10 days, both dermal flaps were harvested and sent for quantitative bacteriology. Due to operative complications, 12 of 15 sheep completed the study. The heated flap temperature was significantly higher 39.2 ± 0.5°C (± SE) vs. the control flap 36.1 ± 0.1°C (p < 0.00001) and bacterial counts were significantly smaller in the heated flap (median 1.0 × 10⁷ colony-forming units per gm tissue) when compared to the control flap (median 7.5 × 10⁷) (p = 0.001). This study shows the use of a noncontact radiant heat bandage controls ischemic soft tissue infections in an ovine model.