Listeria monocytogenes meningitis in adults. Sixteen consecutive cases 1973-1982.

16 adult patients with Listeria monocytogenes meningitis were reviewed to see whether clinical features or initial laboratory findings could discriminate between these patients and patients with purulent meningitis of other causes. Six patients suffered from known predisposing diseases and 4 were alcoholics. The initial clinical picture was indistinguishable from meningitis of other causes. Microscopy of cerebrospinal fluid (CSF) was negative in all cases but 2 where gram-positive rods were seen. CSF cytology and biochemistry could not discriminate from other causes of purulent meningitis although a low leucocyte content and a low percentage of neutrophils were often present. All L. monocytogenes strains isolated were sensitive to ampicillin and aminoglycosides whereas susceptibility to other antibiotics was low or varying. In adult patients suffering from purulent meningitis initial therapy should include ampicillin until an etiological diagnosis is established. The same is true in some cases of febrile encephalopathy with low content of neutrophils in CSF, especially when the glucose content is low.