STED super-resolution microscopy of biopsies from meningitis patients shows that pIgR and PECAM-1 are expressed on the BBB endothelium and colocalize with pneumococci. Immunofluorescent staining using STED super-resolution microscopy of six human biopsies from patients who died of pneumococcal meningitis caused by different serotypes. Each row shows images related to the section of one blood vessel selected as representative among 10 blood vessels/patient imaged (per each staining). (A) Immunofluorescent detection of pIgR, PECAM-1, and endothelial marker shows colocalization of the two receptors on the BBB endothelium. (B) Immunofluorescent detection of S. pneumoniae, pIgR, and PECAM-1 shows that most pneumococci colocalize with pIgR and PECAM-1. (C) Immunofluorescent detection of pIgR and PECAM-1 shows that the two receptors colocalize in many areas of the brain vasculature. Bars, 10 µm.