What is the role of dexamethasone (corticosteroid) in the treatment of meningitis?

Why We Give Dexamethasone in Bacterial Meningitis

Dexamethasone is given to reduce the inflammatory response in the subarachnoid space that causes neurological damage, hearing loss, and death in bacterial meningitis, and should be started immediately with or before the first dose of antibiotics in all adults and children with suspected bacterial meningitis. 1

Mechanism of Action

Dexamethasone works by attenuating the host inflammatory cascade that causes most of the pathological damage in bacterial meningitis. 2, 3

• The inflammatory response, not the bacteria themselves, causes the majority of neurological injury through release of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1, and platelet-activating factor) when bacteria invade the meninges 2, 3
• Dexamethasone reduces cerebral edema, decreases intracranial pressure, improves cerebral perfusion, prevents cerebral vasculitis, and blocks cytokine-mediated neuronal injury 4, 3
• The steroid must be given before or with antibiotics to prevent the massive inflammatory surge that occurs when bacteriolytic antibiotics cause bacterial lysis 5, 1

Evidence for Mortality and Morbidity Benefit

The strongest evidence comes from the 2002 European Dexamethasone Study, which showed dexamethasone reduced unfavorable outcomes from 25% to 15% and mortality from 34% to 14% in adults with bacterial meningitis. 6

• For pneumococcal meningitis specifically, dexamethasone reduced unfavorable outcomes from 52% to 26%, representing the most dramatic benefit 6, 1
• Dexamethasone significantly reduces hearing loss and neurological sequelae across all bacterial meningitis cases, though it does not reduce overall mortality when all pathogens are combined 5, 1
• In children, dexamethasone reduces neurological and audiological sequelae from 38% to 14% when given before antibiotics 3

Dosing and Timing Protocol

Adults: 10 mg IV every 6 hours for 4 days 5, 1, 6

Children: 0.15 mg/kg IV every 6 hours for 4 days 5, 1, 3

Critical timing requirement: Dexamethasone must be administered 10-20 minutes before or simultaneously with the first antibiotic dose 5, 1, 3. If not given with the first dose, it can still be started up to 4 hours after antibiotics are initiated 5.

Pathogen-Specific Considerations

Continue dexamethasone for:

• Streptococcus pneumoniae - strongest evidence for mortality reduction 1, 6
• Haemophilus influenzae type b - confirmed benefit for reducing hearing loss 1

Discontinue dexamethasone for:

• Listeria monocytogenes - associated with increased mortality (13% of patients treated had higher death rates in French cohort) 5, 1

Neutral effect (clinician discretion):

• Neisseria meningitidis - no clear harm or benefit, decision can be individualized 5

Geographic and Resource Considerations

The benefit of dexamethasone is only established in high-income countries with high standards of medical care. 5, 1

• Studies in low-income countries showed no benefit, likely due to differences in healthcare infrastructure, delayed presentation, and HIV prevalence 5
• This geographic limitation is critical when applying these guidelines globally 1

Special Populations Where Dexamethasone is NOT Recommended

Neonates (<1 month): Current evidence insufficient; not recommended 5

Cryptococcal meningitis: May worsen outcomes; not recommended 1

Tuberculous meningitis: Different indication - dexamethasone IS strongly recommended but with different dosing (12 mg/day for adults initially for 3 weeks, then tapered over 3 weeks) 7

Common Pitfalls to Avoid

• Do not delay antibiotics to give dexamethasone - they should be given together or dexamethasone slightly before 5, 6
• Do not continue dexamethasone if Listeria is identified - this is associated with harm 5, 1
• Do not use dexamethasone in neonatal meningitis - evidence is insufficient and one small trial showed imbalanced treatment groups 5
• Be aware that dexamethasone decreases CSF penetration of vancomycin and ceftriaxone, which raises theoretical concerns in antibiotic-resistant pneumococcal meningitis, though clinical benefit still outweighs this concern 2