What is the recommended treatment for bacterial meningitis?

Treatment of Bacterial Meningitis

The recommended treatment for bacterial meningitis is immediate administration of a third-generation cephalosporin (ceftriaxone or cefotaxime), with the addition of vancomycin or rifampin if Streptococcus pneumoniae with reduced susceptibility is suspected, and ampicillin for patients over 50 years or those with risk factors for Listeria monocytogenes. 1

Initial Management

• Start antibiotics immediately - Treatment should begin as soon as possible after clinical suspicion of bacterial meningitis, ideally within 1 hour of presentation, even if lumbar puncture is delayed 1
• Dexamethasone adjunctive therapy - Administer 10 mg IV dexamethasone every 6 hours, with the first dose given shortly before or simultaneously with the first antibiotic dose 1
• Continue dexamethasone for 4 days if pneumococcal meningitis is confirmed or suspected; discontinue if another cause is identified 1

Empiric Antibiotic Selection by Age Group

Neonates (<1 month)

• Ampicillin plus cefotaxime or ampicillin plus an aminoglycoside 1
  • Dosing: Cefotaxime 50 mg/kg q8h; ampicillin 50 mg/kg q8h (age <1 week)
  • For age 1-4 weeks: ampicillin 50 mg/kg q6h; cefotaxime 50 mg/kg q6-8h 1

Children (1 month to 18 years)

• Ceftriaxone or cefotaxime plus vancomycin or rifampin 1
  • Ceftriaxone 50 mg/kg q12h (max 2g q12h) or cefotaxime 75 mg/kg q6-8h
  • Vancomycin 10-15 mg/kg q6h to achieve trough levels of 15-20 μg/mL 1

Adults (18-50 years)

• Ceftriaxone or cefotaxime plus vancomycin or rifampin 1
  • Ceftriaxone 2g q12h or 4g q24h; cefotaxime 2g q4-6h
  • Vancomycin 10-20 mg/kg q8-12h to achieve trough levels of 15-20 μg/mL 1

Adults (>50 years or with risk factors for Listeria)

• Ceftriaxone or cefotaxime plus vancomycin or rifampin plus ampicillin 1
  • Add ampicillin 2g q4h to cover Listeria monocytogenes 1
  • Risk factors for Listeria include diabetes mellitus, immunosuppressive drugs, cancer, and other immunocompromising conditions 1

Pathogen-Specific Treatment (After Identification)

Streptococcus pneumoniae

• If penicillin MIC <0.1 μg/mL: Penicillin G or ampicillin 1
• If penicillin MIC 0.1-1.0 μg/mL: Third-generation cephalosporin 1
• If penicillin MIC ≥2.0 μg/mL or cefotaxime/ceftriaxone MIC ≥1.0 μg/mL: Vancomycin plus third-generation cephalosporin 1
• Duration: 10-14 days 1

Neisseria meningitidis

• If penicillin susceptible: Penicillin G or ampicillin 1
• If reduced susceptibility: Third-generation cephalosporin 1
• Duration: 7 days 1

Listeria monocytogenes

• Ampicillin or penicillin G with or without an aminoglycoside 1
• Alternative: Trimethoprim-sulfamethoxazole 1
• Duration: 21 days 2

Haemophilus influenzae

• β-lactamase negative: Ampicillin 1
• β-lactamase positive: Third-generation cephalosporin 1

Culture-negative meningitis

• Continue empiric therapy for at least 2 weeks 1

Critical Care Considerations

• Intensive care referral for patients with rapidly evolving rash, limb ischemia, cardiovascular instability, acid/base disturbance, hypoxia, respiratory compromise, frequent seizures, or altered mental state 1
• Consider intubation for patients with GCS <12 1
• Transfer to critical care for patients with rapidly evolving rash, GCS ≤12 (or drop >2 points), those requiring monitoring or specific organ support, or those with uncontrolled seizures 1

Common Pitfalls and Caveats

• Delayed antibiotic administration is associated with poor outcomes - do not wait for imaging or lumbar puncture results if bacterial meningitis is suspected 1
• Vancomycin should never be used as monotherapy for bacterial meningitis, even for highly resistant pneumococcal strains 1
• Dexamethasone may reduce CSF penetration of vancomycin - when using dexamethasone with suspected resistant pneumococci, consider adding rifampin to the regimen 1
• Rifampin should never be used as monotherapy due to rapid development of resistance 1
• Meropenem can be considered as an alternative to third-generation cephalosporins for bacterial meningitis in children (40 mg/kg every 8 hours, maximum 2g every 8 hours) 3

Duration of Therapy

• S. pneumoniae: 10-14 days 1
• N. meningitidis: 7 days 1
• L. monocytogenes: 21 days 2
• Culture-negative: At least 14 days 1

By following this evidence-based approach to bacterial meningitis treatment, focusing on early antimicrobial therapy with appropriate agents based on age and likely pathogens, along with adjunctive dexamethasone when indicated, the best outcomes for mortality, morbidity, and quality of life can be achieved.