Adult Bacterial Meningitis: Lecture notes

Typical Presentation

  • Fever (75-85%), headache (87%), objective neck stiffness or meningismus (70-83%), signs of cerebral dysfunction such as confusion (69%), delirium or declining consciousness. Triad of fever, neck stiffness and altered mental status in 44%; but at least two of possible tetrad of headache, fever, neck stiffness and altered mental status occur in 95%.
  • Vomiting (35%), seizures (15-30%), cranial nerve palsies or focal neurological signs (23-33%), Kernig’s (9%) or Brudzinski’s signs of meningismus, papilloedema (1%).
  • Jolt accentuation of headache (100% – see Attia paper) !

Newman D. Clinical assessment of meningitis in adults. Ann Emerg Med 2004; 44: 71-3. [Reference]

Attia J, Hatala R, Cook DJ et al. Does this adult patient have acute meningitis? JAMA 1999; 282:175-81. [Reference] (NB The authors’ suggestion in this meta-analysis that absence of jolt accentuation of headache in patients with fever essentially excludes meningitis is flawed, as was based on one 1991 Japanese paper, which had just one actual meningitis case studied!)

Atypical presentation

  • Elderly: lethargy, obtundation, absence of fever and minimal signs meningismus.
  • Neutropenia / immunocompromised: subtle signs due to impaired ability to mount inflammatory response.
  • Neonates, infants and young children: poor feeding, irritability, N&V, fever “a sick looking child with fever has bacterial meningitis / menigococcaemia until proven otherwise.”

Diagnosis

  • 10% lymphocyte predominance in CSF, usually infants with gram negative infection, or in Listeria meningitis.
  • 60-90% positive CSF on gram stain. Drops to 40-60% if prior antibiotics, with blood cultures rarely positive after treatment.
  • Posterior pharyngeal wall isolate (50% patients with systemic disease) or skin film / aspirate from purpuric lesion are useful even after antibiotics.
  • Polymerase chain reaction (PCR) amplification of DNA in blood or CSF ie. N.meningitidis, pneumococcus and for viruses. CSF antigen tests no longer offered routinely (Qld Health).

Management

  • Investigations
    • CT is performed before LP, in order to exclude alternate mass lesion diagnoses such as cerebral abscess, subdural empyema or toxoplasma encephalitis – a normal scan does not exclude raised ICP (see below).
    • Lumbar puncture is contraindicated irrespective of CT findings in shock, widespread rash or evidence of coagulopathy, drowsiness / impaired consciousness, signs of raised ICP (bradycardia, hypertension, papilloedema, periodic breathing), and with focal neurology.

Clark T, Duffell E, Stuart J et al. Lumbar puncture in the management of adults with suspected bacterial meningitis – a survey of practice. J Infection 2006 ;52 :315-19. [Reference]

Hasbun R, Abrahams J et al. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. NEJM 2001; 345:1727-1733. [Reference] (Editorial Steigbigel N. 1768-1770. [Reference])

  • Immediate antibiotic therapy is paramount.
    • Ceftriaxone 4 g (child 100 mg/kg up to 4 g) IV daily or 2 g (50 mg/kg up to 2 g) IV 12-hrly, plus benzylpenicillin 2.4 g (child 60 mg/kg up to 2.4 g) IV 4-hrly if immunosuppressed, or Listeria monocytogenes is suspected.
    • Omit the penicillin (given for Listeria) if patient aged between 3 months to 15 years, unless they are immunosuppressed.
    • Add vancomycin 12.5 mg/kg up to 500 mg IV 6-hrly if Strep. pneumoniae or Staph. aureus are suspected; or neutrophils are in CSF but no organisms seen (and if viral meningitis / meningococcal disease are unlikely).

Therapeutic Guidelines Ltd. Therapeutic Guidelines. Antibiotic; Version 13, 2006.

  • Steroids
    • Dexamethasone 10 mg IV 6-hrly (0.15mg/kg) before or with first dose of antibiotic then 6-hrly for 4 days
    • Reduces mortality (RR 0.76), severe hearing loss (RR 0.36) and long-term neurological sequelae (RR 0.66) overall including children
    • Note data in adults are limited, but greatest benefit if turn out to have pneumococcal infection.

van de Beek D, de Gans J, McIntyre P et al. Corticosteroids for acute bacterial meningitis (Review). Cochrane Database Syst Rev 2007;1:CD004405. [Reference]

de Gans J, van de Beek D. Dexamethasone in adults with bacterial meningitis. NEJM 2002; 347: 1549-56. [Reference] (Editorial Tunkel A, Scheld W. 1613-14. [Reference])

van de Beek D, de Gans J, Spanjaard L et al. Clinical features and prognostic factors in adults with bacterial meningitis. N Eng J Med 2004; 351:1849-59. [Reference]

Heyderman R, Lambert H, O’Sullivan I et al. Early management of suspected bacterial meningitis and meningococcal septicaemia in adults. J Infection 2003; 46: 75-7. [Reference] (Editorial: Cohen J. Management of bacterial meningitis in adults. BMJ 2003; 326: 996-7. [Reference])

Algorithm: Early management of suspected bacterial meningitis and meningococcal septicaemia in adults. [Reference and PDF] http://www.meningitis.org

Beaman M, Wesselingh S. Acute community-acquired meningitis and encephalitis. MJA 2002; 176:389-396. [Reference]

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