Overview
Definition
An acute purulent infection within the subarachnoid space.
Epidemiology
A medical emergency. Incidence decreased dramatically with Hib and Pneumococcal vaccines.
Etiology & Risk Factors
- Streptococcus pneumoniae
- Neisseria meningitidis
- Listeria monocytogenes (in elderly/neonates/immunocompromised)
- Group B Strep (in neonates)
Clinical Symptoms
- Classic Triad: Fever, Nuchal rigidity (stiff neck), Altered mental status
- Headache
- Photophobia
- Petechial rash (N. meningitidis)
Clinical Approach
Diagnosis
- Lumbar Puncture (CSF analysis: high opening pressure, >1000 WBCs with PMN predominance, low glucose, high protein)
- Blood cultures
- Head CT (perform before LP if signs of increased ICP or focal neuro deficits)
Management
- EMPIRIC ANTIBIOTICS IMMEDIATELY (Do not delay for LP/CT)
- Adults: Ceftriaxone + Vancomycin
- Adults > 50 / Immunocompromised: Ceftriaxone + Vancomycin + Ampicillin (for Listeria)
- Dexamethasone (give before or with first dose of antibiotics to prevent hearing loss)
Complications
- Seizures
- Hearing loss
- Cerebral edema
- Cognitive impairment
- Death