In Vitro Bactericidal Activity of Blood for Pasteurella Tularensis

Abstract

The bactericidal activity of various species of mammalian whole blood for P. tularensis was determined under controlled conditions, and was found to vary among the species tested. The whole blood of the cow, dog, and sheep were found to exhibit a significant amount of bactericidal activity resulting in a decrease of 1 log in the number of bacteria inoculated; the whole blood of the other species tested showed much smaller amounts of activity. The bactericidal activity of dog blood was equally effective against concentrations of bacteria ranging from 101 to 107 organisms per ml of final test mixture.The bactericidal activity of the species tested correlated to some degree with the resistance of these animals to experimental infections with P. tularensis.The bactericidal complex in the blood in the case of the dog resides in the plasma fraction. The experimental results do not suggest that the complex resides in the cells and diffuses into the plasma, where its effect is demonstrated.