Inflammatory response is associated with critical colonization in combat wounds.

BACKGROUND: Modern combat- or blast-related injuries are characterized by devastatingly massive zones of injury that violate soft tissue, bone, and neurovascular structures. In our translational research program, we have determined that healing of traumatic combat wounds is dependent on the immune response. Although the majority of combat wounds are not critically colonized with bacteria, there exists a correlation between critical colonization and the concentration of inflammatory cytokines and chemokines measured in wound effluent or patient serum.
METHODS: Patients with penetrating extremity wounds sustained during combat operations were studied prospectively, being followed for 30 days after definitive wound closure. Surgical debridement was repeated every 48-72 h until wound closure at the discretion of the attending surgeon. Serum, wound effluent, and wound bed tissue biopsy were collected at each debridement. Serum and wound effluent were analyzed with a multiplex assay for cytokines, chemokines, and inflammatory proteases, whereas wound tissue was assessed for microbial colonization via quantitative cultures. Correlations between serum and effluent cytokines and chemokines and the degree of tissue colonization were evaluated.
RESULTS: Samples from 154 debridements in 38 wounds from 25 male patients were investigated. Many of the patients sustained multi-system trauma (mean Injury Severity Score 21±12 points) and were critically ill (mean Acute Physiology and Chronic Health Evaluation II score 7±5 points). Healing failure occurred in 23.7% of wounds. A marked inflammatory profile, including increased serum and wound effluent cytokines and chemokines, was associated with the extent of critical colonization.
CONCLUSIONS: The correlation between systemic and local inflammatory cytokines and quantitative culture suggests that the interplay between the systemic response to injury and the local wound environment is a determinant of outcome. This relationship remains ill defined and requires further investigation in both clinical and pre-clinical studies. A biomarker panel reflective of colonization may provide clinically useful, objective criteria indicating when wound closure is appropriate for successful healing.