Meningitis

Adult

Background

• Microbiology
  • Bacterial meningitis:
    • Pneumococcus (60%), meningococcus (15%), GBS (15%), H flu (7%), listeria (2%)
  • Viral meningitis
    • Echo, coxsackie, entero (85%)
    • HSV, CMV
• Pathophysiology
  • Hematogenous spread via respiratory tract
  • 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

Diagnosis

Measure	Bacterial	Viral	Fungal	Neoplastic
Opening Pressure	>30	<30	~30	~20
WBC 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	Pos	neg	India ink

^For bloody tap, subtract 1 WBC for every 250 RBC

DDX

1. Encephalitis
2. Brain mass
3. Brain abscess
4. SAH
5. Migraine

Work-Up

1. CBC
2. Chem
3. Blood cx
4. ?CT head: See CT Before Lumbar Puncture
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
   5. Hold (Tube 4)

Treatment

1. Abx
   1. Give as soon as possible (if LP performed w/in 2hr of abx CSF culture will not be affected)
   2. Guidelines
      1. Age 18-50y
         1. Ceftriaxone 2gm IV q12hr + vancomycin 15mg/kg q8-12hr
            1. (vancomycin is for resistant pneumococcus)
      2. Age >50y
         1. Ceftriaxone 2gm IV q12hr + vancomycin 15mg/kg q8-12hr + ampicillin 2gm IV q4h
            1. (Ampicillin is for listeria)
      3. CSF leak w/ history of closed head trauma
         1. Ceftriaxone 2gm IV q12hr + vancomycin 15mg/kg q8-12hr
      4. History of recent penetrating head injury, neurosurgery, CSF shunt
         1. (Ceftazidime 2gm IV q8hr or cefepime or meropenem) + vanco 25 milligrams/kg load
      5. Meningitis due to sinusitis
         1. Ceftriaxone + metronidazole
2. Dexamethasone
   1. Only give prior to or w/ first dose of abx
   2. 10mg IV q6hr x4d
3. Mannitol
   1. For marked cerebral edema
4. Acyclovir
   1. Consider for pts w/ suspected viral menengitis who present w/ neuro deficits
   2. 10mg/kg IV q8hr (Obese patients should be dosed using ideal body weight)

Prophylaxis

• For meningococcus exposure
  • Indications:
    • Household contacts
    • School or day care contacts in previous 7d
    • Direct exposure to pt's secretions (kissing, shared utensils or toothbrush)
    • Intubation without facemask
  • Meds
    • Rifampin 600mg PO BID x2d OR CTX 250mg IM x1 OR ciprofloxacin 500mg PO x1

Disposition

1. Bacterial meningitis
   1. Admit w/ droplet precautions
2. Viral meningitis
   1. Admit for empiric abx until culture results return OR
   2. Discharge w/ 24hr f/u

Pediatric

Background

• Meningismus is difficult to discern if <6mo, (esp if <2mo)
• <3months old
  • 1% incidence of bacterial meningitis
  • E. coli, Group B strep, listeria
• >3months old
  • S. pneumo, meningococcus, staph

Diagnosis

Bacterial Meningitis Score for >2mo and well-appearing

• Risk Factor
  • Peripheral blood ANC >10K
  • Seizure
  • CSF
    • CSF ANC >1000
    • CSF protein >80
    • CSF Gram stain (if + 61% Sn, 99% Sp)

• Any risk factor = high risk for bacterial meningitis
• Very low risk if infant lacks all risk factors

Work-Up

1. CBC
2. CSF

Disposition

• Admit despite negative meningitis score if:
  • Age <2mo w/ any degree of pleocytosis
  • Appear ill
  • Infants w/ aseptic meningitis
• If likely viral meningitis still give ceftriaxone x 1, f/u in 24hr

Source

Tintinalli, Lexicomp