Treatment of Bacterial Meningitis
Immediate Empirical Antibiotic Therapy
Start ceftriaxone 2g IV every 12 hours (or cefotaxime 2g IV every 6 hours) immediately after obtaining blood cultures, even before lumbar puncture results are available. 1, 2
Age-Based Empirical Regimens
For adults <60 years:
- Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 1, 2
- Add vancomycin 15-20mg/kg IV twice daily OR rifampicin 600mg twice daily if penicillin-resistant pneumococci is suspected based on local resistance patterns 2
For adults ≥60 years:
- Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours PLUS amoxicillin 2g IV every 4 hours for Listeria coverage 1, 2
- This combination is mandatory in this age group since ceftriaxone has no activity against Listeria monocytogenes 3
Administration Details
- Administer ceftriaxone intravenously over 30 minutes in adults 4
- Do not use calcium-containing diluents (Ringer's solution, Hartmann's solution) as precipitation can occur 4
- Maximum daily dose should not exceed 4 grams 4
Pathogen-Specific Definitive Therapy
Once culture results identify the causative organism, narrow therapy accordingly:
Streptococcus pneumoniae:
- Benzylpenicillin 2.4g IV every 4 hours if penicillin-sensitive 1, 2
- Continue ceftriaxone/cefotaxime if penicillin-resistant or intermediate susceptibility 1
- Duration: 10-14 days 1, 2
- For strains with decreased cephalosporin susceptibility, high-dose cefotaxime (300 mg/kg/day, maximum 24g/day) has proven effective 5
Neisseria meningitidis:
- Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours OR benzylpenicillin 2.4g IV every 4 hours 1, 2
- Duration: 5 days 1, 2
- For suspected meningococcal sepsis with typical petechial/purpuric rash, treatment can be stopped if recovered by day 5 even without lumbar puncture confirmation 1
Listeria monocytogenes:
- Amoxicillin 2g IV every 4 hours 1, 2
- Duration: 21 days 1, 2
- Ceftriaxone and other cephalosporins have NO activity against Listeria 3
Haemophilus influenzae:
- Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 1, 2
- Duration: 10 days 1, 2
- Effective against both beta-lactamase producing and non-producing strains 6, 7
Gram-negative bacilli (E. coli, Klebsiella, Proteus):
- Continue ceftriaxone/cefotaxime 1
- Seek specialist infectious disease consultation regarding local resistance patterns 1
- Duration: 21 days 1
Adjunctive Dexamethasone Therapy
Consider dexamethasone as adjunctive therapy for suspected bacterial meningitis, especially for pneumococcal meningitis. 1, 2
- Dexamethasone may help block the inflammatory response from antibiotic-induced release of endotoxin and cell wall components 3
- This is particularly important given ceftriaxone's rapid bactericidal activity 3
Special Considerations and Pitfalls
Travel history is critical:
- Check recent travel to countries with high pneumococcal resistance rates 1, 2
- Consult local infectious disease expertise for up-to-date resistance patterns 1, 2
Duration for unidentified pathogens:
- If no pathogen is identified and patient has recovered, discontinue treatment by day 10 1
Outpatient transition:
- Consider outpatient IV therapy for clinically well patients 1
Common pitfall - Chlamydia coverage:
- If Chlamydia trachomatis is suspected (particularly in pelvic inflammatory disease), add appropriate antichlamydial coverage as ceftriaxone has no activity against this organism 4
Streptococcus pyogenes:
- When treating infections caused by Streptococcus pyogenes, continue therapy for at least 10 days 4
No dose adjustment needed:
- No dosage adjustment is necessary for renal or hepatic impairment in adults receiving up to 2 grams per day 4