Guidelines for managing acute bacterial meningitis

Nearly one in four adults with acute bacterial meningitis will die, and many survivors sustain neurological deficits.¹,² The outcome has not changed since the early 1960s despite the introduction of potent antibiotics and specialised intensive care units.³

The prognosis is worse with a delay in management.⁴ Consequently, the outcome depends on whether the attending physician suspects acute bacterial meningitis, and whether the healthcare system is set up to make a rapid, accurate diagnosis and initiate fast and effective treatment.

In this respect, standardised guidelines such as those recently issued by the working party under the British Infection Society are invaluable.⁵ These guidelines make recommendations for the management of adults with suspected or diagnosed acute bacterial meningitis or meningococcal disease and for the prevention of secondary cases by vaccination and prophylactic antibiotic treatment. The guidelines may provide a template for treating acute bacterial meningitis for doctors in most countries. However countries that now vaccinate against Haemophilus influenzae type B or meningococci serogroup C may see a change in the epidemiology of meningococcal disease.

There is little evidence on the best way to manage patients as soon as they present with acute bacterial meningitis. The new report advises family doctors to give benzylpenicillin to anyone they suspect has acute bacterial meningitis before he or she is admitted to hospital. With elderly patients, however, more caution may be needed. Firstly, the outcome from acute bacterial meningitis has not been shown to be improved by preadmission antibiotics; the crucial factor is probably whether the attending doctor suspects acute bacterial meningitis at all and therefore arranges immediate admission to hospital. Secondly, preadmission antibiotics may make it harder to get a microbial diagnosis.

For a young patient with suspected meningococcal disease, the immediate use of antibiotics followed by rapid admission to hospital may be the best course of action. In the case of suspected bacterial meningitis of other causes it may be more reasonable to arrange rapid transfer to hospital followed by speedy microbiological tests and antibiotic treatment. After admission to hospital, the widely accepted empirical treatment is a third generation cephalosporine, such as cefotaxim or ceftriaxone, with ampicillin if listerial meningitis cannot be ruled out. In patients with obvious meningococcal disease, penicillin is the drug of choice.

The reduced susceptibility of pneumococci to penicillin is an increasing problem in large parts of the world; this may often be overcome by increasing the amount and frequency of doses, but rifampicin may be useful for pneumococci that are truly penicillin resistant.⁶ Selecting the appropriate treatment for patients with acute bacterial meningitis who are hypersensitive to β lactams is difficult. Chloramphenicol is not ideal because of its low clinical efficacy and potential side effects; meropenem or broad spectrum quinolones may be considered, although there is little evidence they work.

Supportive treatment has been hotly debated. Corticosteroids reduce neurological deficits in children with Haemophilus influenzae meningitis, whereas their beneficial effect in adults remains to be proved.⁷ Hopefully, the results of the multicentre European trial on dexamethasone in acute bacterial meningitis, scheduled to end within a year, will provide conclusive evidence. Glycerol or mannitol may reduce intracranial pressure when there is intracranial hypertension.⁸ The need for full fluid replacement and maintenance is rightfully emphasised in the guidelines. Fluid restriction does not improve either brain oedema or outcome in patients with acute bacterial meningitis.⁹,¹⁰ Furthermore, cerebral perfusion depends on mean arterial blood pressure in these patients and is adversely affected by hypovolaemia.¹¹ Also these patients are at risk of sepsis with hypotension. In general, many patients with acute bacterial meningitis need intensive care to monitor and treat both cerebral and extracerebral complications.

The guidelines should be disseminated to all physicians. An increased awareness of acute bacterial meningitis with emphasis on speedy diagnosis and treatment will serve patients well.