Bacterial Meningitis: Indications for Dexamethasone
Primary Recommendation
Empiric dexamethasone should be started immediately with or before the first dose of antibiotics in all adults and children with suspected bacterial meningitis in high-income countries, then tailored based on pathogen identification. 1
Dosing Regimens
- Adults: 10 mg IV every 6 hours for 4 days 1
- Children: 0.15 mg/kg IV every 6 hours for 4 days 1
- Neonates: Dexamethasone is NOT recommended due to insufficient evidence 1
Timing of Administration
Dexamethasone must be given with or before the first antibiotic dose to prevent the inflammatory response from antibiotic-induced bacterial lysis. 1
- If antibiotics have already been started, dexamethasone can still be initiated up to 4 hours after the first antibiotic dose, though this is based on expert consensus rather than trial data 1
- Beyond 4 hours, the benefit becomes uncertain 1
Pathogen-Specific Continuation Decisions
Continue Dexamethasone (Full 4-Day Course):
- Streptococcus pneumoniae: Strong evidence for mortality reduction (21% absolute reduction) and decreased neurological sequelae 1, 2
- Haemophilus influenzae type b: Confirmed benefit for reducing hearing loss (OR 0.31) 1
Discontinue Dexamethasone:
- Listeria monocytogenes: A French cohort study of 252 patients demonstrated increased mortality when dexamethasone was given within 24 hours 3
- Neisseria meningitidis: No significant benefit demonstrated, though safe to use 1
- Non-bacterial etiology confirmed: Stop immediately 1
Special Considerations:
- Cryptococcal meningitis: NOT recommended as standard therapy; may worsen outcomes 3
- Tuberculous meningitis: Strongly recommended with different dosing (12 mg/day for adults ≥25 kg, 8 mg/day for children <25 kg, tapered over 6 weeks total) 4
Evidence-Based Benefits
Dexamethasone significantly reduces hearing loss and neurological sequelae but does NOT reduce overall mortality across all bacterial meningitis cases. 1
Specific Outcomes:
- Reduces hearing loss overall (particularly in H. influenzae and S. pneumoniae) 1
- Reduces neurological sequelae 1, 5
- Reduces mortality specifically in pneumococcal meningitis 1, 2, 5
- Reduces both systemic and neurological complications during hospitalization 2
- No excess adverse effects compared to placebo in high-quality trials 1
Geographic and Resource Considerations
The benefit of dexamethasone is only established in high-income countries with high standards of medical care. 1
- Studies from low-income countries showed no beneficial effect 1
- This likely reflects differences in disease severity at presentation, antibiotic availability, and supportive care capabilities 1
Critical Pitfalls to Avoid
Antibiotic Penetration Concerns:
- Dexamethasone decreases CSF penetration of vancomycin and may delay CSF sterilization 6
- This is particularly concerning with antibiotic-resistant S. pneumoniae 6
- Solution: Ensure adequate antibiotic dosing and use combination therapy (vancomycin plus third-generation cephalosporin) for suspected resistant pneumococcal meningitis 1
Listeria Risk:
- Patients >50 years old and immunocompromised should receive empirical ampicillin/amoxicillin coverage from the start (in addition to cephalosporin) to cover Listeria 3
- If Listeria is subsequently identified, immediately discontinue dexamethasone 3
HIV-Associated Tuberculous Meningitis:
- Evidence for dexamethasone benefit is limited in HIV-positive patients with tuberculous meningitis 7
- Delay ART initiation for 8 weeks due to IRIS concerns 7
Clinical Algorithm
- Suspected bacterial meningitis → Start dexamethasone immediately with first antibiotic dose 1
- Pathogen identified as S. pneumoniae or H. influenzae → Continue full 4-day course 1, 3
- Pathogen identified as L. monocytogenes → Stop dexamethasone immediately 3
- Pathogen identified as N. meningitidis → Consider stopping (no proven benefit, though safe) 1
- Non-bacterial etiology confirmed → Stop dexamethasone 1