Meningitis

Background

• Microbiology
  • Bacterial meningitis:
    • Pneumococcus (60%), meningococcus (15%), GBS (15%), H flu (7%), listeria (2%)
• Pathophysiology
  • Hematogenous spread via respiratory tract OR
  • Contiguous spread (otitis media, sinusitis, brain abscess)

Risk Factors

1. Otitis media
2. Sinusitis
3. Immunosuppression/splenectomy
4. Alcoholism
5. Pneumonia
6. DM
7. CSF leak
8. Endocarditis
9. Neurosurgical procedure / head injury
10. Indwelling neurosurgical device / cochlear implant
11. Malignancy

Clinical Features

• Almost all patients present w/ at least 2 of the following:
  • Headache
  • Fever
  • Neck stiffness
  • Altered mental status
• Also may have:
  • Photophobia
  • Vomiting
  • Prodromal URI
  • Focal neuro sx (e.g.CN deficit)
  • Seizure (25%)
• Jolt Test (100% Sn)
  • Have pt rapidly shake head L and R; if does not bother pt unlikely to have meningitis

Classification

1. Acute (<24hr)
   1. Usually bacterial in origin (25%)
2. Subacute (1-7d)
   1. Viral or bacterial
3. Chronic (>7d)
   1. Viral, TB, syphilis, fungi, carcinomatous

Differential Diagnosis

1. encephalitis
2. brain mass
3. brain abscess
4. subarachnoid hemorrhage
5. migraine

Work-Up

1. Droplet precautions (if suspect bacterial meningitis)
2. CBC, chemistry, coags
3. Blood cx
4. CT head
   1. Consider LP w/o CT if:
      1. Normal mental status
      2. Normal neuro exam
      3. No immunocompromise
      4. No papilledema or normal optic nerve sheath diameter
5. CXR (50% of pts w/ pneumoccocal meningitis have e/o pna on CXR)
6. CSF studies
   1. Glucose and protein (Tube 1)
   2. Gram stain and culture (Tube 2)
   3. Cell count and differential (Tube 3)
   4. Special studies if indicated (HSV PCR, india ink) - Tube 2

Interpreting CSF

Measure	Bacterial	Viral	Fungal	Neoplastic
Opening Pressure	↑↑	Normal, mild ↑	Normal, mild ↑	Normal, mild ↑
Cell Count	>1000	<1000	<500	<500
% PMNs	>80%	1-50%	1-50%	1-50%
Glucose	<40	>40	<40	<40
Protein	>200	<200	>200	>200
Gram Stain	+ (80% effective)	neg	AFB, India ink

Treatment

1. Abx
   1. Give as soon as possible (if given w/in 2hr of LP CSF culture will not be affected)
   2. Vancomycin for penicillin-resistant pneumococci; ampicillin for listeria
   3. Guidelines
      1. Age 18-50y
         1. CTX 2gm IV q12hr + vancomycin 15mg/kg q8-12hr
      2. Age >50y
         1. CTX 2gm IV q12hr + vancomycin 15mg/kg q8-12hr + ampicillin 2gm IV q4h
      3. CSF leak w/ history of closed head trauma
         1. CTX 2gm IV q12hr + vancomycin 15mg/kg q8-12hr
      4. History of recent penetrating head injury, neurosurgery, CSF shunt
         1. Vanco 25 milligrams/kg load + (ceftazidime 2gm IV q8hr or ceftazidime or meropenem)
2. Dexamethasone
   1. Only give prior to or w/ first dose of abx
   2. 10mg IV q6hr x4d

Prophylaxis

• For N. meningitis exposure
  • Close contact to nasopharyngeal secretions or those who were w/ the pt at least 4hr during week before onset of symptoms
  • Cipro 500mg PO x 1 or rifampin x 4 doses or ceftriaxone x1

Source

Tintinalli