Experimental melioidosis in inbred mouse strains

Experimental infection was induced in three inbred mouse strains (BALB/c, BDF1 hybrid and C57BL) by i. p. inoculation with Pseudomonas pseudomallei. The bacterial load in the viscera and the host response induced in different compartments (blood, peritoneal cavity and organs) were determined. Blood cell parameters and peritoneal exudative cell populations were evaluated during the infection with the aid of an automated haematology analyser Technicon H-1. It was found that all mouse strains produced a similar intraperitoneal inflammatory response with predominance of granulocytes at the early stage of infection and subsequent increase of macrophages especially in BDF1 hybrid and BALB/c mice. The highest bacterial count found in the liver and spleen of C57BL was associated with corresponding tissue damage (purulent pneumonia, abscesses in liver, karyorrhexis of hepatocytes and meningoencephalitis). The degree of bacterial load and histological changes found in BALB/c and BDF1 hybrid mice were lower than in C57BL mice. The results show that the variations in the infection magnitude among inbred mouse strains are host-dependent.