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