HaemophilllS injlllenzae Meningitis in Infant Rats after

An animal model permitting study of bacterial meningitis has been developed in infant rats by the intranasal inoculation of H aemophilus influenzae b. Seventy-three percent (29 of 40) of five-day-old animals were bacteremic 48 hr after inoculation with 107 H. influenzae b; of those with bacteremia, 79 % had docu-mented meningitis. Studies with fluorescein-labeled specific antiserum suggested that bacteria were dispersed in the upper respiratory tract, penetrated the nasal mucosa, entered the systemic circulation, and spread to the meninges from the dorsal longitudinal and lateral dural sinuses. The histologic appearance of the meningitis in infant rats was similar to that reported from specimens taken 'at human autopsy. Bacterial meningitis in young children continues to be a serious problem. In the United States, there are an estimated 40,000 cases each year [1], of which the majority are in children less than five years of age [2-6]. Haemophilus in[luenzae b ac