External ventricular drain infections are difficult to identify with current diagnostic methods. Initiation of antibiotic treatment is usually supported by indirect methods of bacterial infection, such as clinical signs or cerebrospinal fluid cell counts (CSF). As such, excessive treatment with antibiotics is common in these patients due to suspected infection while the incidence of true culture confirmed infections are less common. This study will evaluate three novel diagnostic methods for rapid direct bacterial detection in CSF, in order to assess if these can be used to guide antibiotic treatment in neurocritically ill patients, compared to CSF bacterial cultures.