Ventricular involvement in experimental Hemophilus influenzae meningitis.

We determined the frequency of ventricular involvement during Hemophilus influenzae type b meningitis in ten bacteremic infant rhesus monkeys. Meningitis was defined as cerebrospinal fluid obtained from the lumbar subarachnoid space or cisterna magna containing bacteria and ten or more leukocytes per mm3. HIB were cultured from 22 of 22 ventricular CSF samples. In 17 of 18 comparisons of bacterial density in ventricular and cisternal CSF, the values were within one log10: similarly, 5 of 8 quantitative ventricular-lumbar comparisons were within one log10. This concordance was present at bacterial densities of 2 x 10(1) to 1 x 10(9) CFU/ml. When discordance was present, the ventricular CSF contained more bacteria. In 15 of 20 comparisons of leukocyte density in ventricular and cisternal CSF, the ventricular pleocytosis was lower (mean ventricular/cisternal ratio 0.08). We conclude that infection of the lateral cerebral ventricle is a uniform feature of HIB meningitis in infant monkeys, but the cellular inflammatory component is less.