The Journal of Medical Microbiology, Vol 36, Issue 5 312-317, Copyright © 1992 by Society for General Microbiology
Experimental rabbit model of meningitis produced by Haemophilus influenzae serotype c
P. Sulc, B. Hengstler, G. Krinke, T. O'Reilly and O. Zak
Department of Pharma Research, CIBA-GEIGY Limited, Basel, Switzerland.
The virulence of Haemophilus influenzae type c when inoculated
intracisternally (i.c.) into rabbits was evaluated. Rabbits are relatively
resistant to infection with H. influenzae type b, such that inocula of the
order of 10(6-9) cfu are required to produce meningitis in this model. In
contrast, fatal meningitis was produced in this study when 10(3) cfu of a
type-c strain were injected i.c. into rabbits. Numbers of bacteria in
cerebrospinal fluid (CSF) of control (untreated) animals generally
increased to 10(7) cfu/ml. Increases in white blood cells, protein and
lactate in the CSF were similar to those which had been observed during
meningitis due to Streptococcus pneumoniae in rabbits. The infection was
amenable to therapy with ampicillin 50 mg/kg given intravenously 12 h after
infection. Numbers of bacteria in CSF were reduced to 2.2 x 10(3) cfu/ml
(SEM 0.2 x 10(3)) at 8 h after treatment with a single dose of ampicillin.
Two doses of ampicillin, given 12 and 20 h after infection, significantly
increased the mean survival time. In contrast to previous experimental
studies with rabbits, the penetration of ampicillin into the CSF was
high--46 (SEM 10) % of the blood level. Since considerable replication of
H. influenzae type c occurred within the CSF in this model, the nature of
the meningeal damage produced was likely to be similar to that which takes
place in man. Hence, H. influenzae type c meningitis in rabbits may provide
a useful model in which therapeutic and other experimental studies of H.
influenzae meningitis can be performed.
