Interactions of Haemophilus influenzae with human endothelial cells in vitro.

Haemophilus influenzae is a major causative agent of bacterial meningitis in children in the United Kingdom and elsewhere. The bacterium normally invades its human host via the respiratory mucosal epithelium and disseminates to blood and other tissues. How virulent strains ofH. influenzae traverse the respiratory epithelial and vascular endothelial cellular barriers is still poorly understood. Studies using the infant rat model of meningitis suggest that the bacterium may enter the blood by direct invasion of the blood vessels in the subepithelial tissues of the nasopharynx [ 1 ]. Also, it has been shown that bacteremia invariably precedes meningitis [2]. A possible means of entry into the central nervous system could be translocation across the brain vascular endothelial cells. Studies on the interactions of other