Pathological and biochemical features of Legionella pneumophila infection in guinea-pigs

The main pathological feature of experimental legionellosis produced by the intraperitoneal inoculation of guinea-pigs was a fibrinopurulent peritonitis, especially over the liver and spleen. Foci of necrosis were present in these organs from the second to seventh day after infection. Early biochemical changes in the serum included significant decreases in the concentration of zinc and iron, and increases in copper and triglycerides. Phenylalanine to tyrosine ratios increased strikingly, but free amino acid decreased slightly. The total protein concentration did not change, but acute-phase proteins increased. Serum lysozyme activity increased as leucocytosis developed but fell during the subsequent leucopenia. In the later stages of the disease the activity of alkaline phosphatase, gamma-glutamyl transpeptidase, and creatine kinase decreased; that of dehydrogenases and transaminase increased.