Penetration of fimbriate enteric bacteria through basement membranes: a hypothesis.

A mechanism for penetration of basement membranes by Escherichia coli is presented. The mechanism is based on the ability of the S fimbriae of meningitis-associated E. coli to bind to vascular endothelium and choroid plexuses in brain and to basement membranes. On the other hand, the S and the type 1 fimbriae of E. coli immobilize plasminogen and tissue-type plasminogen activator; this process generates proteolytic plasmin activity on the surface of fimbriate cells. Our hypothesis is that bacterium-bound plasma activity, directed to basement membranes through fimbrial binding, promotes bacterial penetration through basement membranes.