Effect of Burns in Rats on Defense Mechanisms Against Pseudomonas Aeruginosa

Investigation of the decreased resistance of severely burned rats to Pseudomonas aeruginosa revealed that certain antibacterial defense mechanisms were altered. Both the phagocytic activity and the capacity for intracellular destruction of bacteria by the fixed phagocytic cells of the spleen and liver were impaired as a result of burning. The cellular response to superficial skin trauma or peritoneal irritation was markedly depressed for 24 hours after the thermal injury, although it surpassed normal values 72 hours after burning. Evidence has been presented that the localization of P. aeruginosa in nonburned areas (the brain and muscle) of the burned rats contributed to the establishment of infection. Even though the activity of some of the organs of the reticuloendothelial system was diminished,the initial clearance of organisms from the blood stream of burned rats was the same as that for normal rats. Burning produced no significant impairment of the bactericidal activity of serum, and, in fact, increased activity was observed in the serum of rats which had been burned 24 hours previously.