What are the treatment regimens and doses for bacterial, viral, and fungal meningitis?

Treatment of Meningitis: Dosing Regimens

Bacterial Meningitis

For empiric treatment of bacterial meningitis in adults, administer ceftriaxone 2g IV every 12 hours (total 4g daily), with the addition of vancomycin 15-20 mg/kg IV every 12 hours if penicillin-resistant pneumococci is suspected, and add amoxicillin 2g IV every 4 hours for patients ≥60 years old to cover Listeria monocytogenes. 1

Empiric Therapy Algorithm

Age-based approach:

• Adults <60 years: Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 1
• Adults ≥60 years: Same cephalosporin regimen PLUS amoxicillin 2g IV every 4 hours 1
• Add vancomycin 15-20 mg/kg IV every 12 hours (targeting trough levels 15-20 μg/mL) OR rifampicin 600mg twice daily if penicillin-resistant pneumococci suspected (recent travel to high-resistance areas) 1

Alternative if cephalosporins contraindicated:

• Adults <60 years: Chloramphenicol 25 mg/kg IV every 6 hours 1
• Adults ≥60 years: Chloramphenicol 25 mg/kg IV every 6 hours PLUS co-trimoxazole 10-20 mg/kg (trimethoprim component) in four divided doses 1

Pathogen-Specific Therapy

Once organism identified, tailor therapy:

Streptococcus pneumoniae:

• Penicillin-sensitive: Benzylpenicillin 2.4g IV every 4 hours OR continue ceftriaxone 2g IV every 12 hours 2, 1
• Penicillin-resistant but cephalosporin-sensitive: Continue ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 2, 1
• Penicillin AND cephalosporin-resistant: Ceftriaxone or cefotaxime PLUS vancomycin PLUS rifampin 600mg twice daily 2
• Duration: 10-14 days (10 days if recovered by day 10; extend to 14 days if not recovered or if resistant organism) 2, 1

Neisseria meningitidis:

• Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 1
• Alternative: Benzylpenicillin 2.4g IV every 4 hours 1
• Duration: 5-7 days 3, 1

Haemophilus influenzae:

• Ceftriaxone 2g IV every 12 hours 3
• Duration: 10 days 3

Listeria monocytogenes:

• Amoxicillin 2g IV every 4 hours (already included in empiric regimen for ≥60 years) 1
• Duration: 21 days 3

Enterobacteriaceae:

• Ceftriaxone 2g IV every 12 hours 3
• Duration: 21 days 3

Staphylococcal species:

• MSSA: Nafcillin or oxacillin; alternatives include vancomycin or meropenem 2
• MRSA: Vancomycin 15-20 mg/kg IV every 12 hours, consider adding rifampin 600mg IV/orally every 12 hours 2
• Duration: 14 days 2

Post-Neurosurgical Meningitis

Empiric regimen: Vancomycin 15-20 mg/kg IV every 12 hours PLUS one of the following: 2

• Ceftazidime 2g IV every 6 hours, OR
• Cefepime 2g IV every 8 hours, OR
• Meropenem 2g IV every 8 hours

Duration: 10-14 days for uncomplicated cases with good clinical response; extend if delayed response 2

Critical consideration: If CSF shunt present and infected, remove all shunt components in addition to antimicrobial therapy 2

Pediatric Dosing

Meningitis: Initial dose 100 mg/kg ceftriaxone (maximum 4g), then 100 mg/kg/day (maximum 4g daily) given once daily or divided every 12 hours 4

Duration: 7-14 days typically 4

Neonates (22-60 days): Ceftriaxone 50 mg/kg once daily for bacteremia/UTI; avoid ceftriaxone for neonatal meningitis 22-28 days—use ampicillin plus ceftazidime every 8 hours instead 3

Critical caveat: Administer IV doses over 60 minutes in neonates to reduce bilirubin encephalopathy risk 4

Important Clinical Considerations

Dosing frequency matters for CNS penetration: While once-daily ceftriaxone dosing has been studied and shows efficacy 5, 6, current guidelines uniformly recommend twice-daily dosing (2g every 12 hours) for the first 24-48 hours to ensure rapid CSF sterilization and adequate concentrations throughout the dosing interval 3. After clinical improvement and organism susceptibility confirmed, some institutions reduce to once-daily dosing 7.

Monitoring parameters:

• Clinical response daily: fever, neck stiffness, mental status 1
• Vancomycin trough levels: maintain 15-20 μg/mL 1
• Consider repeat CSF analysis if no improvement after 48-72 hours 1

Administration pitfalls to avoid:

• Never mix ceftriaxone with calcium-containing solutions—can cause fatal precipitation 4
• Vancomycin must be infused over ≥60 minutes to avoid infusion reactions 1
• In neonates, ceftriaxone infusion must be over 60 minutes 4

Viral Meningitis

Viral meningitis is typically self-limited and requires supportive care only. Specific antiviral therapy is reserved for:

Herpes simplex virus (HSV) meningitis/encephalitis:

• Acyclovir 10 mg/kg IV every 8 hours for 14-21 days (based on general medical knowledge)

Varicella-zoster virus (VZV):

• Acyclovir 10-15 mg/kg IV every 8 hours for 10-14 days (based on general medical knowledge)

Fungal Meningitis

Cryptococcal meningitis (most common fungal cause):

• Induction: Liposomal amphotericin B 3-4 mg/kg/day IV PLUS flucytosine 100 mg/kg/day divided every 6 hours for ≥2 weeks (based on general medical knowledge)
• Consolidation: Fluconazole 400-800 mg daily for 8 weeks (based on general medical knowledge)
• Maintenance: Fluconazole 200 mg daily for ≥1 year (based on general medical knowledge)

Candida meningitis:

• Liposomal amphotericin B 5 mg/kg/day IV PLUS flucytosine 100 mg/kg/day divided every 6 hours (based on general medical knowledge)