Infection of the central nervous system by Listeria monocytogenes: a review of 54 adult and juvenile cases.

The clinical features in 54 juvenile and adult patients with Listeria monocytogenes infection of the central nervous system are described. Thirty-one of the patients had pre-existing chronic disease; the remainder were previously healthy. Twenty of the patients, the 'meningo-encephalitic group' developed focal neurological signs. The remaining 34, the 'meningitic group' exhibited no focal signs other than those caused by increased intracranial pressure. The 'meningitic group' differed from the 'meningo-encephalitic group' in that the cerebrospinal fluid white cell count, protein and glucose levels were markedly more abnormal and the prognosis worse. Evidence of septicaemia was found only in the 'meningitic group'. Meningo-encephalitis may represent a modified response to listerial infection typified by granulomatous rather than a suppurative response. The predominance of this response that was demonstrated in females may indicate partial immunity, the result of previous Listeria monocytogenes colonisation of the female genital tract. Listeria monocytogenes infection is treatable and should be considered in patients with meningitic or encephalitic illness. Repeated blood cultures may be required to establish the diagnosis.