Rhombencephalitis due to Listeria monocytogenes is a frequent complication of 
human listeriosis, inducing a high mortality and severe neurological sequelae 
despite antibiotic therapy. However, there is no animal model which consistently 
reproduces clinical rhombencephalitis. Here, we present a model of Listeria 
rhombencephalitis in gerbils. Animals were inoculated in the middle ears with a 
low infective dose of L. monocytogenes, thus creating prolonged otitis media 
with persistent bacteremia. Gerbils developed a severe rhombencephalitis with 
circling syndrome, paresia, ataxia, rolling movements. The invasion of the 
central nervous system was visualized on living animals by resonance magnetic 
imaging and characterized by bacterial growth in the brain, reaching about 10(7) 
bacteria in the rhombencephalum by day 12 of infection. The histological lesions 
were mainly located in the brainstem, and consisted in coalescent, necrotic 
abscesses with perivascular sheaths, mimicking those observed in human 
rhombencephalitis. Bacteria were detected by electronmicroscopy inside 
infectious foci, either free in necrotic material or inside inflammatory cells, 
mainly polymorphonuclear cells. This gerbil model of Listeria rhombencephalitis 
will be useful to study the molecular mechanisms allowing bacteria to cross the 
blood-brain barrier, and to evaluate the intracerebral efficacy of antibiotics.