Recommended Antibiotic Regimen for Bacterial Meningitis
The recommended empiric antibiotic regimen for bacterial meningitis should be based on patient age and local resistance patterns, with immediate administration (within 1 hour of hospital entry) being critical for reducing mortality and neurological sequelae. 1, 2
Initial Management Principles
- Antibiotic therapy must be started as soon as possible after bacterial meningitis is suspected, with the time period from hospital entry to antibiotic administration not exceeding 1 hour 1, 2
- Blood cultures should be obtained before initiating antibiotics 2
- If lumbar puncture is delayed (e.g., due to need for cranial CT), empiric treatment must be started immediately upon clinical suspicion, even before diagnostic confirmation 1, 2
- Delay in treatment is strongly associated with increased mortality and poor neurological outcomes 2
Empiric Antibiotic Regimens by Age Group
Neonates (<1 month)
- Recommended regimen: Amoxicillin/ampicillin/penicillin plus cefotaxime, or amoxicillin/ampicillin plus an aminoglycoside 1
- Dosing:
- Age <1 week: cefotaxime 50 mg/kg q8h; ampicillin/amoxicillin 50 mg/kg q8h; gentamicin 2.5 mg/kg q12h
- Age 1-4 weeks: ampicillin 50 mg/kg q6h; cefotaxime 50 mg/kg q6-8h; gentamicin 2.5 mg/kg q8h 1
Children (1 month to 18 years)
Adults (18-50 years)
- Recommended regimen: Cefotaxime or ceftriaxone plus vancomycin or rifampicin 1, 2
- Dosing:
- Ceftriaxone 2 g q12h or 4 g q24h
- Cefotaxime 2 g q4-6h
- Vancomycin 10-20 mg/kg q8-12h (to achieve serum trough concentrations of 15-20 μg/mL)
- Rifampicin 300 mg q12h 1
Older Adults (>50 years) or Immunocompromised Patients
- Recommended regimen: Cefotaxime or ceftriaxone plus vancomycin or rifampicin plus amoxicillin/ampicillin/penicillin G 1, 2
- Dosing:
- Ceftriaxone 2 g q12h or 4 g q24h
- Cefotaxime 2 g q4-6h
- Vancomycin 10-20 mg/kg q8-12h (to achieve serum trough concentrations of 15-20 μg/mL)
- Rifampicin 300 mg q12h
- Amoxicillin or ampicillin 2 g q4h 1
Special Considerations
- In areas with high pneumococcal resistance to penicillin, vancomycin should be added to the empiric regimen 1, 2
- Risk factors for Listeria monocytogenes include age >50 years, diabetes mellitus, immunosuppressive drugs, cancer, and other immunocompromising conditions 1, 2
- For meningitis due to Listeria monocytogenes, amoxicillin during 3 weeks, associated with gentamycin or cotrimoxazole is recommended 3
- Meropenem is FDA-approved for bacterial meningitis in pediatric patients 3 months and older caused by H. influenzae, N. meningitidis, and penicillin-susceptible S. pneumoniae at a dose of 40 mg/kg every 8 hours (maximum 2 grams every 8 hours) 4
Duration of Treatment
- For specific pathogens, treatment duration should be tailored:
- For culture-negative bacterial meningitis, continue empiric treatment for a minimum of 2 weeks 1
- Short-course antibiotic therapy is not recommended in children and adults with bacterial meningitis 1
Adjunctive Therapy
- Dexamethasone should be administered with or before the first dose of antibiotics in suspected bacterial meningitis 1, 2
- Dexamethasone can still be started up to 4 hours after the first dose of antibiotics 1
- Corticosteroids reduce mortality in pneumococcal meningitis and decrease overall hearing loss and neurologic sequelae 1
Common Pitfalls to Avoid
- Delaying antibiotic administration for imaging studies 1, 2
- Inadequate coverage for Listeria in patients >50 years or immunocompromised 1, 2
- Insufficient dosing that doesn't achieve adequate CSF penetration 2
- Neglecting to obtain blood cultures before starting antibiotics 2
- Using first-generation cephalosporins, which are not acceptable for treating meningitis 5
- Failing to adjust therapy based on local resistance patterns 1, 2
- Inadequate duration of therapy, especially for culture-negative cases 1