MENINGITIS

Meningitis is acute inflammation of the meninges (the membranes covering the brain). Bacterial meningitis is a notifiable disease.

Causative organisms

  • Most commonly bacterial: Streptococcus pneumoniae, Haemophilus influenzae type b (mainly in young children), Neisseria meningitidis, Enteric bacilli
  • Viral (HSV, enteroviruses, HIV, VZV etc)
  • Cryptococcus neoformans (in the immune-suppressed)
  • Mycobacterium tuberculosis

Clinical features

  • Rapid onset of fever
  • Severe headache and neck stiffness or pain
  • Photophobia
  • Convulsions, altered mental state, confusion, coma
  • In mycobacterial and cryptococcal meningitis, the clinical presentation can be sub-acute , over a period of several days or 1-2 weeks

Differential diagnosis

  • Brain abscess
  • Space-occupying lesions in the brain
  • Drug reactions or intoxications

Investigations

  • CSF: usually cloudy if bacterial, clear if viral. Analyse  for white cell count and type, protein, sugar, Indian-ink staining (for Cryptococcus), gram stain, culture and sensitivity
  • Blood: For serological studies and full blood count
  • Chest X-ray and ultrasound to look for possible primary site

Management

Treatment depends on whether the causative organisms are already identified or not.

General measures

  • IV fluids
  • Control of temperature
  • Nutrition support (NGT if necessary)
Causative organisms not yet identified
  • Start initial appropriate empirical broad spectrum therapy
    • Ceftriaxone 2 g IV or IM every 12 hours for 10-14 days
      Child: 100 mg/kg daily dose given as above
    • Change to cheaper effective antibiotic if and when C&S results become available

If ceftriaxone not available/not improving

  • Use chloramphenicol 1 g IV every 6 hours for up to 14 days (use IM if IV not possible)
    Child: 25 mg/kg per dose

Once clinical improvement occurs

  • Change to 500-750 mg orally every 6 hours to complete the course;
    Child: 25 mg/kg per dose
Causative organisms identified

Streptococcus pneumoniae (10-14 day course; up to 21 days in severe case)

  • Benzylpenicillin 3-4 MU IV or IM every 4 hours
    Child: 100,000 IU/kg per dose
  • Or ceftriaxone 2 g IV or IM every 12 hours
    Child: 100 mg/kg daily dose

Haemophilus influenzae (10 day course)

  • Ceftriaxone 2 g IV or IM every 12 hours
    Child: 100 mg/kg per dose
    Only if the isolate is reported to be susceptible to the particular drug
  • Change to chloramphenicol 1 g IV every 6 hours
    Child: 25 mg/kg per dose
  • Or ampicillin 2-3 g IV every 4-6 hours
    Child: 50 mg/kg per dose

Neisseria meningitidis (up to 14 day course)

  • Benzylpenicillin IV 5-6 MU every 6 hours
    Child: 100,000-150,000 IU/kg every 6 hours
  • Or Ceftriaxone 2 g IV or IM every 12 hours
    Child: 100 mg/kg daily dose
  • Or Chloramphenicol 1 g IV every 6 hours (IM if IV not possible)
    Child: 25 mg/kg IV per dose

Once clinical improvement occurs

  • Change to chloramphenical 500-750 mg orally every 6 hours to complete the course Child: 25 mg/kg per dose

Note: Consider prophylaxis of close contacts (especially children < 5 years):

  • Adults and children >12 years: Ciprofloxacin 500 mg single dose
    Child <12 yrs: 10 mg/kg single dose
  • Alternative (e.g. in pregnancy): ceftriaxone 250 mg IM single dose
    Child < 12 yrs: 150 mg IM single dose

Listeria monocytogenes (at least 3 weeks course)
Common cause of meningitis in neonates and immunosuppressed adults

  • Benzylpenicillin 3 MU IV or IM every 4 hours
  • Or ampicillin 3 g IV every 6 hours

Notes

  • Both medicines are equally effective
  • Therapy may need to be prolonged for up to 6 weeks in some patients

Prevention

  • Avoid overcrowding
  • Improve sanitation and nutrition
  • Prompt treatment of primary infection (e.g. in respiratory tract)
  • Immunisation as per national schedules
  • Mass immunisation if N. Meningitis epidemic