A previously healthy 74-year-old Caucasian man with
penicillin allergy was admitted with evolving
headache,
confusion,
fever, and neck stiffness. Treatment for
bacterial meningitis with
dexamethasone and monotherapy
ceftriaxone was started. The cerebrospinal fluid showed negative microscopy for bacteria, no bacterial growth, and negative polymerase chain reaction for
bacterial DNA. The patient developed
hydrocephalus on a second CT scan of the brain on the 5th day of admission. An external ventricular
catheter was inserted and Listeria monocytogenes grew in the cerebrospinal fluid from the
catheter. The patient had severe neurological sequelae. This case report emphasises the importance of covering empirically for Listeria monocytogenes in all patients with
penicillin allergy with suspected
bacterial meningitis. The case also shows that it is possible to have significant
infection and
inflammation even with negative microscopy, negative cultures, and negative broad range polymerase chain reaction in cases of
Listeria meningitis. Follow-up spinal taps can be necessary to detect the presence of Listeria monocytogenes.