Comparison of the Effects of the CO 2 Laser and Chlorohexidine on the Decontamination of Infected Cutaneous Wounds: A Histologic Study in Rats

Abstract

Objective: The aim of this study was to compare histologically the effects of CO₂ laser and chlorohexidine gluconate (4%) on Staphylococcus aureus-infected cutaneous wounds. Background Data: Wound infection constitutes a big risk for patients, and it is usually associated with increased morbidity, mortality and hospital costs. It is accepted that local treatment of these infections is effective. Materials and Methods: Standardized wounds created on the dorsum of 36 rats were infected with Staphylococcus aureus and treated during 6 days as follows: group I, chlorohexidine gluconate (4%) applied to the wound surface during 1 min during 6 days; group II, single CO₂ laser irradiation (8 W, CW, unfocused, 8-cm focal distance, 81,530 W/cm²), maintaining surface debris; group III, single CO₂ laser irradiation (8 W, CW, unfocused, 8-cm focal distance, 81,530 W/cm²), removing the surface debris. Seven days after wounding, the animals were killed and specimens taken for light microscopy. Results: On control wounds, epithelial ulceration and neutrophylic and lymphoplasmocitary inflammatory infiltrate was observed. On group II, there was epithelial hyperplasia, areas of ulceration and intense neutrophylic and lymphoplasmocitary inflammatory infiltrate. In group III, there was a neutrophylic inflammatory infiltrate underneath the surface debris and below that intense lymphoplasmocitary inflammatory infiltrate. When the surface debris was removed (group IV), there was epithelial ulceration and mild lymphoplasmocitary inflammatory infiltrate and fibroblasts and collagen fibers. Conclusion: The results of this study show that infected wounds treated with 4% chlorohexidine show a more pronounced inflammatory reaction when compared to that observed when the CO₂ laser is used, especially when surface debris are removed; surface debris removal on laser-treated wounds results in better and more rapid healing; the surface debris may act as a culture medium for bacterial growth or, because of its characteristics, it may act as a local irritant and delay healing.