We therefore thought to measure in a purely observational study, blood and CSF vancomycin concentrations in adult patients with pneumococcal meningitis hospitalized in medical intensive care unit that received third-generation cephalosporin, vancomycin and dexamethasone. The aim of the study was to observe whether or not sufficient concentrations of vancomycin could be measured in the CSF despite the concomitant use of dexamethasone. Patients were cared for in a perfectly routine manner. There was no randomization. All patients received routine, recommended care (IDSA guidelines). There was no invasive procedure. Dexamethasone was administered according to the de Gans study (NEJM 2002). In these patients with severe meningitis, a second lumbar puncture was performed as recommended(IDSA Guidelines, CID 2004). At the same time, peripheral blood was taken. In both samples, vancomycin concentration was determined.