Comparative biological features of a rat liver abscess model induced with three Fusobacterium necrophorum strains

Several biological features were compared in a rat liver abscess model, using intraportal inoculations with 3 bovine strains of Fusobacterium necrophorum which varied in virulence. Serum alanine aminotransferase activities were increased significantly (P less than 0.05) in rats inoculated with F necrophorum 2101 by postinoculation hours 6, 12, and 24. Thereafter, alanine aminotransferase values returned to base line for the remainder of the experiment. Also, rats inoculated with F necrophorum 2101 had a significantly greater (P less than 0.05) weight loss than did the control rats during the first 5 postinoculation days and developed leukocytosis characterized by a neutrophilia with a left shift. The duration of the bacteremia was related directly to the virulence of the F necrophorum strain. Fusobacterium necrophorum 2101, a biotype A which was the most virulent, induced the most persistent bacteremia; F necrophorum 2035, a biotype B which was the least virulent, produced the shortest bacteremia; and F necrophorum 2030, a biotype AB which was of intermediate virulence, led to bacteremia of intermediate duration. Plasma endotoxin was demonstrated intermittently during the first 24 hours, but did not correlate with the bacteremia.