ABSTRACT
Localized bacterial colonization of a 30% total body surface burn (TBSB) wound raises the resting metabolic rate of rats. To determine whether endotoxin (LPS) released in the burn wound contributes to this response, the metabolic rates and colonic temperatures of male Sprague-Dawley rats were monitored before and for 1 week after thermal injury. Wounds were seeded with non-virulent P. aeruginosa (NVP), or S. epidermidis (SE) or were left unseeded at the time of injury. Non-bacteremic SE-seeded rats were as hypermetabolic as the NVP-seeded animals on postburn days (PBDs) 3-4 and 7-8, indicating that wound LPS is not an obligatory mediator of postburn hypermetabolism. Continuous subcutaneous infusion of NVPlps (2.6 and 12.6 micrograms/100 gm/hr) beneath unseeded burn wounds did not raise metabolic rates above those of burned, unseeded controls. Neither NVP seeding nor LPS infusion resulted in measurable endotoxemia on PBDs 7-8. These results indicate that the LPS released in the colonized burn wound does not serve as either a circulating mediator or the principal inducer of other mediators of postburn hypermetabolism in rats.
Subject(s)
Burns/metabolism , Endotoxins/metabolism , Pseudomonas aeruginosa , Animals , Body Temperature , Calorimetry , Endotoxins/administration & dosage , Infusions, Parenteral , Male , Metabolic Clearance Rate , Pulmonary Gas Exchange , Rats , Rats, Inbred StrainsABSTRACT
Both clinical and laboratory studies have demonstrated an increased risk of fatal sepsis after splenectomy. The importance of the spleen in clearing a bacterial challenge from pneumococci or other encapsulated organisms is now well accepted. The role of the spleen in handling a bacteremia due to nonencapsulated (Gram negative) organisms is not well established. Rats were subjected to either sham operation or splenectomy. Two weeks after surgery, all animals received 10(6) E. coli by intraperitoneal injection. Tail vein blood samples for quantitative culture were obtained at multiple time intervals after the bacterial challenge. All animals developed a bacteremia. Initially, the mean bloodstream bacterial counts were comparable in the sham and splenectomy groups. Sham-operated rats cleared all bacteria from the bloodstream within 240 minutes. In contrast, 240 minutes after bacterial injection, E. coli could still be recovered from the blood of asplenic rats at levels comparable to those noted at the start of the experiment. The present study shows that splenectomy does impair the animal's ability to clear a Gram-negative bacteremia.
