Indications for CT before LP:

• >60 years old
• Immunocompromised state
• History of CNS disease (mass lesion, stroke, focal infection)
• Seizure within 1 week of presentation
• Altered consciousness / focal neurological deficit

* Patients with suspected meningitis without the above findings are good candidates for LP without CT given their low risk for herniation.

Common Signs/Symptoms:

• Patient’s often present soon after onset of symptoms ~ 24 hours (range 1 hour – 14 days)

Classic Triad:

• Fever (95-77% at presentation)
• Nuchal Rigidity (94-83% at presentation)
• Altered Mental Status (83-78% at presentation)
• *Headache (94-79% at presentation)

*One review of 696 cases of community-acquired bacterial; only 44% had clinical triad, although almost all (95%) had at least 2 of 4 symptoms.

Laboratory Findings (besides CSF):

• Routine blood work is often unrevealing, but leukocytosis can be present
• Serum chemistry may reveal an AG metabolic acidosis or hyponatremia (30% in one study)
• Blood cultures are often positive (50-90% of patients) and can help guide therapy

Common Pathogens:

• Streptococcus pneumoniae (71%)
• Neisseria meningitidis (12%)
• Group B Streptococcus (7%)
• Haemophilus influenza (6%)
• Listeria moncytogenes (4%)

* Percentages based on CDC data of 1083 cases of bacterial meningitis from 2003-2007

Treatment for Suspected Bacterial Meningitis:

• Empiric therapy should be directed at the most likely bacteria and must be started without delay

Typical empiric regimen:

• 3rd generation cephalosporin (Ceftriaxone 2 g IV Q12H or Cefotaxime 2 g IV Q6H)
• Vancomycin 15-20 mg/kg IV Q12H ~ goal trough 15-20 mcg/mL
• Ampicillin in patients > 50 years old

Indications for Steroids:

• Used in attempt to diminish the rate of neurological complications (seizures, hearing loss, cranial nerve deficits, etc.)
• European studies showed a decreased mortality (7% versus 15% with placebo)
• Only indicated for patients with suspected/confirmed S. pneumoniae
• 15 minutes before administration of antimicrobial agents and continued for full course (0.15 mg/kg Q6H for 4 days)  in suspected/confirmed pneumococcal meningitis