Experimental Infection with Pseudomonas aeruginosa in Mice

ABSTRACT Comparative studies on the fate of Pseudomonas aeruginosa in the peritoneal cavity and organs of mice after intraperitoneal inoculation with highly and low virulent strains were made by the viable cell count technique and microscopic observation. A highly virulent strain, after intraperitoneal inoculation in mice, showed resistance to phagocytosis and grew rapidly in the peritoneal cavity. The highly virulent bacteria then entered the blood and invaded organs, and mice died due to septicemia within 12 to 16 hr after inoculation. On the other hand, the low virulent strain was quickly phagocytized and cleared from the mouse body within 12 hr and all inoculated mice survived. These results suggested that the resistance to phagocytosis or the ability of intracellular multiplication in the host would be an important factor for the pathogenesis of the microorganism.