Pathophysiologic glucocorticoid elevations promote bacterial translocation after thermal injury

Thermal injury results in transient elevations of plasma glucocorticoids and promotes translocation of bacteria from the gut to the mesenteric lymph nodes (MLN) in rats. Translocated organisms are quickly cleared following uncomplicated thermal injury. However, subsequent burn wound infection, in temporal association with sustained pathophysiologic elevations of plasma corticosterone, results in the continued presence of enteric bacteria in the MLN. To study the role of sustained pathophysiologic steroid elevations in the mediation of this prolonged bacterial translocation, Wistar rats were randomly placed in groups receiving one of the following: (i) a 30% total body surface area scald injury with placement of a subcutaneous corticosterone pellet, (ii) a 30% total body surface area scald and a sham pellet implantation, (iii) a sham burn and a corticosterone pellet implantation, or (iv) a sham burn and a sham pellet implantation. The animals were sacrificed on days 1 and 4 after injury, and cultures of the MLN, as well as the liver and spleen, were taken. Implantation of corticosterone pellets resulted in sustained elevations of plasma corticosterone compared with controls not receiving corticosterone pellets, similar to results seen in association with injury and infection. These pathophysiologic elevations were associated with the prolonged presence of organisms in the MLN (90% of burned rats with implanted corticosterone pellets versus 25% of rats with uncomplicated burns on postburn day 4; P less than 0.01), but only in the presence of burn injury. Pathophysiologic glucocorticoid elevations did not lead to progression of translocation to the viscera or blood. Thus, the pathophysiologic glucocorticoid response contributes to the translocation of enteric bacteria and their prolonged presence in the MLN after systemic injury.