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Information ⬇

Author(s): David Sprigings and John L. Klein

Consider bacterial meningitis in any patient with fever, headache, neck stiffness or a reduced conscious level: 95% of patients with bacterial meningitis will have at least two of these four features. Bacterial meningitis can also present as septic shock. Management of suspected bacterial meningitis is summarized in Figure 68.1.

Most cases in the developed world are caused by Neisseria meningitidis or Streptococcus pneumoniae. In the context of immunosuppression, alcohol-use disorder or age >60 years, Listeria monocytogenes should also be considered. In resource-poor settings, M. tuberculosis may predominate (Appendix 68.1).

Disorders which can mimic meningitis include subarachnoid haemorrhage (Chapter 67), viral encephalitis (Chapter 69), brain abscess, subdural empyema and cerebral malaria.

Priorities ⬆ ⬇

  1. Review the physiological observations, make a focused clinical assessment (Table 68.1) and arrange urgent investigations (Table 68.2).
  2. If the clinical picture is consistent with bacterial meningitis, and the patient has shock, a reduced conscious level or a petechial/purpuric rash (suggesting meningococcal infection), take blood for culture and immediately start antibiotic therapy (Table 68.3), plus adjunctive dexamethasone (Table 68.4), if indicated.

  3. In patients with suspected meningitis without signs of shock or severe sepsis, lumbar puncture (LP) should be performed within 1h of arrival at hospital, provided there is no contraindication to LP. Antibiotic therapy (Table 68.3) should be started immediately after LP, and within the first hour.

    If LP cannot be done within 1h (e.g. because of the need for CT or the presence of a coagulopathy), take blood for culture and immediately start antibiotic therapy (Table 68.3).

  4. CT should be done before LP if there are risk factors for an intracranial mass lesion, or signs of raised intracranial pressure:
    • Immunosuppression (e.g. HIV/AIDS, immunosuppressive therapy)
    • History of brain tumour or focal infection
    • Major seizures within one week of presentation
    • Papilloedema
    • Reduced conscious level (Glasgow Coma Scale score <13)
    • Focal neurological signs (not including cranial nerve palsies)
  5. If the patient is taking antiplatelet or anticoagulant therapy, or has thrombocytopenia or a coagulopathy, discuss management with a haematologist before LP. See also Chapters 102 and 103.
  6. The technique of LP is described in detail in Chapter 122.
    • Measure and record the opening pressure. If the opening pressure is >40cm CSF, indicating severe cerebral oedema, give mannitol 0.5g/kg IV over 10 min plus dexamethasone 12 mg IV. Discuss further management with a neurologist.
    • Send CSF for cell count, protein concentration, glucose (fluoride tube), Gram stain and culture. PCR for meningococcus and pneumococcus should be undertaken if blood/CSF cultures are negative. Consider requesting microscopy and culture for acid-fast bacilli if tuberculosis is suspected (Appendix 68.1); in immunosuppressed patients (especially those with HIV infection), request an India ink stain and a cryptococcal antigen test (Appendix 68.2).
  7. Patients with suspected bacterial meningitis should be isolated (contact precautions) until at least 24h into treatment.
  8. Blood-stained CSF may be due to a traumatic tap or subarachnoid haemorrhage. The presence of bilirubin in the CSF (detected by spectrophotometry) indicates red cell breakdown products and confirms subarachnoid haemorrhage (Chapter 67).

Further Management ⬆ ⬇

  1. If organisms are seen on Gram stain of the CSF, bacterial meningitis is confirmed. The cell count will usually be high, with a polymorphonuclear leucocytosis, but may be low in overwhelming infection or immunosuppression. Modify or start antibiotic therapy (Table 68.3). Ask advice from a microbiologist or infectious diseases physician on the best antibiotic regimen and duration of treatment.
  2. If no organisms are seen on Gram stain, management is directed by the clinical picture and CSF formula (Table 68.5):
    • Normal cell count: that is, bacterial meningitis highly unlikely. Consider other infectious diseases which may give rise to meningism (e.g. bacterial tonsillitis).
    • High polymorph count: this is typical of pyogenic bacterial meningitis, although may occur early in the course of viral meningitis. Modify or start antibiotic therapy (Table 68.3). Ask advice from a microbiologist or infectious diseases physician on the best antibiotic regimen and duration of treatment.
    • High lymphocyte count: this may be seen in many diseases (Table 68.6). Distinguishing between viral and partially treated pyogenic bacterial meningitis can be difficult. If in doubt, start antibiotic therapy, awaiting the results of culture of blood and CSF. If tuberculous or cryptococcal meningitis is possible on clinical grounds (see Appendices 68.1 and 68.2), or on the results of CSF examination, ask for microscopy and culture for acid-fast bacilli and an India ink stain/cryptococcal antigen test.
  3. Supportive care of the patient with bacterial meningitis includes:
    • Analgesia as required (e.g. paracetamol, NSAID or codeine).
    • Control of seizures (See chapter 16).
    • Attention to fluid balance. Losses are increased due to fever. Aim for an intake of 2–3L/day, supplementing oral intake with IV normal saline/5% glucose if needed. Check creatinine and electrolytes initially daily. Hyponatraemia may occur due to inappropriate ADH secretion.
  4. Contacts of patients with confirmed or suspected meningococcal meningitis should be identified. Ciprofloxacin (500 mg stat PO for adults) should be offered to household contacts and other close contacts (e.g. sexual partners). Rifampicin (600 mg twice daily PO in adults for two days) is an alternative.
  5. The district community medicine specialist should be informed promptly about confirmed cases of meningitis.

Further Reading ⬆

Brouwer MC, Tunkel AR, McKhann IIGM, van deBeek D (2014) Brain abscess. N Engl J Med 371, 447–456.

Jarrin I, Sellier P, Lopes A (2016) Etiologies and management of aseptic meningitis in patients admitted to an internal medicine department. Medicine 95, e2372. Open access.

McGill F, Heyderman RS, Michael BD, et al. (2016) The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults. Journal of Infection 72, 405–438. Open access. http://www.journalofinfection.com/article/S0163-4453(16)00024-4/pdf