Reticuloendothelial phagocytic response to bacterial challenge after traumatic shock

Abstract

Resistance to intravenous (IV) and intraperitoneal (IP) bacterial challenge during periods of reticuloendothelial (RE) depression following trauma as well as the influence of bacteremia on RE phagocytosis were studied. The experimental shock model utilized was the anesthetized (2 mg/100 g sodium pentobarbital) male rat subjected to nonlethal Noble-Collip drum trauma. During post-traumatic RE depression (60 min after injury) rats were challenged IV or IP with Escherichia coli (1.02 X 10(10)). The clearance half-time of the bacterial load injected intravenously in controls was 1.23 +/- 0.10 min. In contrast, the half-time was 3.62 +/- 0.69 min after sublethal trauma (p less than 0.005) and associated with prolonged blood bacterial retention. Pulmonary localization of E. coli administered either IV or IP was elevated in traumatized rats. Comparison of routes of bacterial challenge with respect to blood levels of viable bacteria suggested lower host bacterial resistance to the IP injection as opposed to the IV route of administration. Production of experimental bacteremia in normal rats resulted in a 39% depression (p less than 0.01) of RE test colloid clearance rate accompanied by a 49% increase (p less than 0.01) in pulmonary colloid localization. The data suggest that depressed systemic RE clearance capacity following trauma may decrease systemic resistance to septicemia, and that severe bacteremia may further undermine the functional state of the reticuloendothelial system.