The bacteriology has changed since beginning of antibiotic therapy. Reports of literature and the dates of patients treated in Neurosurgical Clinic of Münster are analyzed. The improvement of microbiological technique leads to the evidence of a greater role of anaerobics and of a smaller part of sterile cultures. The success of therapy depends on the early beginning of specific therapy. The poor prognosis of the sterile inflammations is caused by inefficiency of unspecific therapy.