How Does Streptococcus pneumoniae Invade the Brain?

Streptococcus pneumoniae (the pneumococcus) is the major cause of bacterial meningitis. The mechanisms by which pneumococci from the bloodstream penetrate the blood-brain barrier to reach the brain are not fully understood. Receptor-mediated adhesion of the bacteria to the brain endothelium is considered a key event leading to meningitis development. The aim of this review is to discuss recent advances and perspectives related to the interactions of S. pneumoniae with the blood-brain barrier during the events leading to meningitis. Altogether, the available data suggest that, by precisely defining the pathways and ligands by which S. pneumoniae adheres to specific receptors, it may be possible to interfere with the respective mechanisms and develop strategies to prevent or even cure pneumococcal meningitis.