0521779407-01 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 20:45
Acute Bacterial Meningitis 19■Fever, nuchal rigidity, signs of cerebral dysfunction; 50% with Neis-
seria meningitidis meningitis have an erythematous, macular rash
that progresses to petechiae or purpura
■Cranial nerve palsies (III, VI, VII, VIII) in 10–20%
■Elderly may to have lethargy or obtundation without fever,+/−
meningismus
tests
Laboratory
■Basic Blood Tests:
➣Elevated WBC
■Specific Diagnostic Tests:
➣Blood cultures are often positive
➣Typical cerebrospinal fluid (CSF) in bacterial meningitis
(normal): opening pressure >180 mm H 2 O (50–150); color tur-
bid (clear); WBC >1000/mm^3 with polymorphonuclear cell pre-
dominance (5); protein >100 mg/dL (15–45); glucose <40 mg/dL
(40–80); CSF/blood glucose ratio <0.4 (>0.6); Gram stain of CSF
shows organisms in 60–90%
➣Culture of CSF is positive in 70–85%; community-acquired acute
bacterial meningitis caused by Streptococcus pneumoniae,
Neisseria meningitidis, Listeria monocytogenes, Haemophilus
influenzae, Escherichia coli, group B streptococcus
➣Antigen testing for specific pathogens appropriate when a puru-
lent CSF specimen has a negative Gram stain and culture, sensi-
tivity 80%
■Other Tests:
➣Patients with evidence of ICP such as coma or papilledema or
focal neurologic findings (seizures, cranial neuropathies) should
have a noncontrast CT scan prior to lumbar puncture (LP); begin
antibiotics before CT scan
differential diagnosis
■Bacteremia, sepsis, brain abscess, seizure disorder, aseptic menin-
gitis (CSF WBC usually 100–1000/mm^3 , eventually with lympho-
cyte predominance), skull fracture, chronic meningitis, encephalitis,
migraine headache, rickettsial infection, drug reaction
management
What to Do First
■Medical emergency: do not delay appropriate antibiotic therapy
■Quick neurologic exam looking for focality or evidence of increased
ICP