Infections of the Central Nervous System

Inclusion Criteria: * All patients aged ≥18 years admitted to the University Hospital Basel with confirmed infectious meningitis and/or encephalitis as principal and/or secondary diagnosis from January 2006 to December 2021 with or without cranial CT prior to LP * All patients aged ≥18 years admitted to the University Hospital Basel over the same time period with suspected infectious meningitis and/or encephalitis as principal and/or secondary diagnosis with or without cranial CT Exclusion Criteria: * Patients without suspected infectious meningitis and/or encephalitis. * Patients with the diagnosis of meningitis/encephalitis confirmed prior to hospital admission * Patients who have refused "General Consent" (i.e., written agreement of patients which allows the further use of their collected medical data for research purposes in encoded form).