An experimental model for pyogenic liver abscess

We have developed a reproducible small-animal model for pyogenic liver abscess, suitable for investigating diagnostic and therapeutic modalities. Male New Zealand white rabbits weighing 2-3 kg were anaesthetized and the liver exposed. Gentle pressure was applied with forceps to the right hepatic lobe. A suspension of 10(5) colony forming units (cfu) Escherichia coli plus Fusobacterium necrophorum (10(6) cfu) plus Bacteroides fragilis (10(6) cfu) was immediately injected into a mesenteric vein. Two weeks later a palpable mass (mean diameter 4 cm) had developed. Thick pus could be aspirated percutaneously. Necropsy revealed a single, but often multiloculated, abscess at the site of the previous trauma. Injection of E. coli alone did not produce any abscesses and B. fragilis alone only small abscesses, with low and variable frequency. Inoculation with F. necrophorum alone produced large abscesses, and a dose-response relationship was established. This is a simple and reliable small-animal model useful in studies of imaging techniques, antibiotic regimens and invasive treatments for pyogenic liver abscess.