12.10.12 Meningitis

Sites

• • Leptomeninges

    • Acute meningitis

  • Parenchyma

    • Encephalitis

  • Venticles

    • Ventriculitis

Organisms (Big 3)

• • Meningococcus

    • Neisseria meningitides

      • B > C > A

    • Commonest in all ages except neonates

    • Treat with 3rd gen. cephalosporin (better than Ben Pen due to resistance)

  • HIB

    • Vaccine introduced 1992

    • Now less common

    • 70% of cases are in children <2

    • Chloramphenicol / 3rd gen cephalosporin

  • Pneumococcus

    • Strep. pneumoniae

Atypical organisms

• • Neonates (Little 3)

    • E. coli

    • GBS

    • L. monocytogenes

  • Aseptic

    • TB

    • Viruses

    • Fungal (esp. in immunosuppressed)

Presentation

• • Fever

  • Vomiting

  • Lethargy

  • Quiet; Little spontaneous movement

  • Petechial rash esp. on limbs

  • Neck stiffness

    • Move head quickly forwards + see if it flops onto chest

  • Joint/muscle pain

  • Photophobia

  • Headache

  • Bulging fontanelle

TB meningitis

• • Remember:

    • Maximise CSF tap

    • Do direct microscopy

    • Special culture

  • Treatment

    • Rif

    • Iso

    • Eth

    • Pyraz

Viral meningitis

• • Causes >50% of cases

  • Causes:

    • Echoviruses

    • Coxsackie A + B

    • Polio

    • Mumps

    • Lymphocytic choriomeningitis virus

    • HSV

  • Mostly untreatable

    • But use acyclovir for HSV

Cells

• • WCC

    • Bact: >5000

    • TB <1000

    • Normal: 3

  • Gram stains

    • Big 3

      • N. meningitidis

        • Gram -ve cocci

      • H. influenzae

        • Gram -ve rods

        • Some very short

      • Strep. pneumonia

        • Gram +ve cocci

    • Little 3

      • E. coli

        • Gram -ve rods

      • GBS

        • Gram +ve cocci, chains

      • L. monocytogenes

        • Gram +ve rods

Prophylaxis

• • Rifampicin for Meningococcal / HIB meningitis

    • Or ciprofloxacin in adults

Vaccines

• • NO vaccine against Meningococcus type B (most common strain)

    • Vaccines for A + B

  • Routine immunisation (2, 3, 4 months) for HIB

Other CNS infections

• • Viral encephilitis

    • Uncommon

    • Serious/fatal in some cases

    • Looks clinically like meningitis

    • Organisms:

      • HSV 1+2

      • Enteroviruses

      • Mumps

      • Measles

      • V. zoster

      • EBV

      • CMV

      • Adenovirus

      • Arboviruses

        • Arthropod-borne

      • Rabies

  • Post infectious syndromes

    • Demyelinating syndrome after viral infection

  • Cerebral abscess

    • Very mixed farmyard of bacteria

      • Gram +ves => Penicillins

        • Strep. milleri

        • Beta-haemolytic Strep

        • S. pneumoniae

        • S. aureus

      • Anaerobes => Metronidazole

        • Bacteroides

        • Fusobacterium

        • Veilonella

        • Anaerobic cocci

    • Treat surgically by drainage

  • Slow virus infections

  • Spongiform encephalopathies

  • CNS infections in AIDS

Notes

• • Prevalence greater in winter

  • One of the only illnesses where treatment precedes diagnosis

    • IV/IM Ben Pen

      • 1200 mg >10

      • 600 mg 1-9 yrs

      • 300 mg infants

  • DON'T do an LP if raised ICP!

    • => Coning

  • Xanthochromia in CSF

    • Old bleed

  • Gram -ve look pink

  • Must notify CDC