Hemophilus influenzae type b meningitis in infant rabbits. Pathogenesis and therapy

V. H. San Joaquin, H. R. Stutman and M. I. Marks

A model of human Hemophilus influenzae type b meningitis was developed in infant rabbits infected intranasally. The pathogenesis and course resembled that in human beings; bacteremia was followed by meningitis with a high mortality. Pretreatment of the nasopharyngeal mucosa with 0.5% trypsin or normal saline significantly increased the rate of bacteremia. Death was age related. Intranasal challenge with type f and nontypeable H influenzae was associated with transient bacteremia. Our results suggest that factors on the respiratory tract epithelial cell surface influence colonization and infection with H influenzae type b and confirm the importance of other host and parasite factors. Intravenous aztreonam resulted in a peak CSF concentration that was 6% to 7% of the serum concentration in infected meninges but only 2% to 3% in normal meninges. Aztreonam reduced mortality in established H influenzae type b meningitis from 88% in untreated animals to 9%.