Figure 1.

Histological analysis of a case of meningococcal septic shock showing bacterial colonies in cerebral capillaries. Paraffin-embedded brain section samples were either analyzed by Gram-Weigert staining (A and B) or by immunohistochemistry with a polyclonal antibody directed against the strain cultured from the blood of this patient (C–F). (A) Brain section showing a bacterial microcolony inside a capillary. (B) Enlargement of the inset in A showing individual bacteria in the colony. (C) Two small colonies (arrowheads) visualized by immunohistochemistry. (D) Example of a large colony surrounded by edema. (E) Illustration of the favored localization of bacterial colonies in capillaries as opposed to arterioles. The arrowhead points to an arteriole and the arrow points to a connected capillary containing bacteria. (F) Enlargement of the inset in E. Arrowheads indicate immuno-labeled bacterial colonies present in the capillary.