Fusobacterium necrophorum infection in mice as a model for the study of liver abscess formation and induction of immunity.

A mouse model is described in which intraperitoneal injection of Fusobacterium necrophorum results in chronic liver abscesses. Viable bacterial counts from mouse lung, liver, and spleen were obtained after whole organ homogenization. From 2 h to 5 days postchallenge, liver was found to contain more bacteria than lung on a per gram basis. Bacterial counts from liver and spleen were about the same during the first 8 h; thereafter liver was found to contain more bacteria. By day 13, though bacterial counts were equivalent in the three organs, abscesses were only observed in liver. This predilection for the liver may be due to a nutritional and/or microenvironmental factor(s). Blood cultures of infected mice revealed a general lack of bacteremia. Extended immunization with formalin-killed cells was found to protect mice against F. necrophorum infection.