Effects of Topical Spray and Foam Formulations on Killing Planktonic Staphylococcus Aureus Bacteria on Porcine Skin Explants

Introduction: Bacterial bioburden consisting of planktonic and biofilm bacteria has been implicated in promoting chronic inflammation that results in highly elevated levels of proteases and reactive oxygen species that destroy proteins that are essential for healing. We evaluated the effects of novel spray or foam formulations on kill planktonic bacteria grown on an ex vivo model of chronic skin wounds.

Materials and Methods: Deep partial thickness injuries created on sterile pig skin explants were inoculated with 4 x 106 CFU of planktonic Staphylococcus aureus (SA113) and incubated for 30 minutes at room temperature then explants were treated with 10 pumps of an antimicrobial solution or treated with a 3 mm thick layer of antimicrobial foam formulation or with sterile saline solution, and explants were transferred to 37ï‚°C incubator. After 24 and 48 hours of incubation, levels of total viable bacteria were measured.

Results: Treatment of SA113 planktonic bacteria on the explants with the foam formulation reduced CFU by 2.5 logs at 24 hours of incubation and totally eliminated all viable bacteria (~8-logs) after 48 hours of incubation. Treatment of SA113 planktonic bacteria on the explants with the spray formulation reduced CFU by 3-logs at 24 hours of incubation, but level of viable bacteria rebounded to near control levels (saline solution spray) at 48 hours of incubation.

Conclusions: Foam and spray formulations had different effects on SA113 planktonic bacteria on pig skin explants. The foam formulation reduced SA113 ~2.5-logs after 24 hours of exposure and totally eliminated planktonic Staphylococcus aureus after 48 hours of exposure. In contrast, the spray formulation only reduced levels of SA113 planktonic at 24 hours.