What is the treatment for bacterial meningitis?

Treatment of Bacterial Meningitis

Immediate Management: Time is Brain

Antibiotic therapy must be initiated within 1 hour of presentation for suspected bacterial meningitis, as delay is strongly associated with increased mortality and poor neurological outcomes. 1, 2

Critical First Steps (Within 60 Minutes)

• Obtain blood cultures immediately before antibiotics, but never delay antibiotic administration beyond 1 hour waiting for cultures or imaging 1, 2
• If lumbar puncture is delayed for any reason (need for CT imaging, coagulopathy, hemodynamic instability), start empiric antibiotics immediately on clinical suspicion 1, 3
• Administer adjunctive dexamethasone 10 mg IV every 6 hours (or 0.15 mg/kg every 6 hours in children) 10-20 minutes before or simultaneously with the first antibiotic dose 4, 2

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Empiric Antibiotic Regimens by Age and Risk Factors

Neonates (0-3 months)

• Ampicillin 50 mg/kg IV every 6-8 hours PLUS cefotaxime 50 mg/kg IV every 6-8 hours 2
• This regimen covers Group B Streptococcus, E. coli, and Listeria monocytogenes 1

Children (3 months to <18 years)

• Ceftriaxone 50 mg/kg IV every 12 hours (maximum 2g every 12 hours) OR cefotaxime 75 mg/kg IV every 6-8 hours PLUS vancomycin 10-15 mg/kg IV every 6 hours (target trough 15-20 mg/mL) 1, 2
• For bacterial meningitis in pediatric patients ≥3 months, meropenem 40 mg/kg every 8 hours (maximum 2 grams every 8 hours) is FDA-approved for H. influenzae, N. meningitidis, and penicillin-susceptible S. pneumoniae 5

Adults <50 Years Without Immunocompromise

• Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 4-6 hours PLUS vancomycin 15-20 mg/kg IV every 8-12 hours (target trough 15-20 mg/mL) 4, 1, 2
• Vancomycin is essential in areas with high pneumococcal resistance to penicillin 1

Adults ≥50 Years or Immunocompromised

• Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 4-6 hours PLUS vancomycin 15-20 mg/kg IV every 8-12 hours PLUS ampicillin 2g IV every 4 hours 1, 2
• The addition of ampicillin is critical for Listeria monocytogenes coverage, as this pathogen is not covered by cephalosporins 1, 2
• Risk factors for Listeria include age >50 years, diabetes mellitus, immunosuppressive drugs, cancer, and other immunocompromising conditions 1

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Adjunctive Dexamethasone Therapy

Dexamethasone reduces mortality and neurological sequelae in pneumococcal meningitis and should be administered to all adults and children with suspected bacterial meningitis. 4, 2

Administration Protocol

• Give dexamethasone 10 mg IV every 6 hours (0.15 mg/kg every 6 hours in children) before or with the first antibiotic dose 4, 2
• Continue for 2-4 days if pneumococcal or H. influenzae meningitis is confirmed 2
• Discontinue if Pseudomonas is identified, as dexamethasone may worsen outcomes in gram-negative meningitis 2

Evidence Base

• A Cochrane meta-analysis of 25 RCTs including 4,121 patients found that corticosteroids decreased overall hearing loss and neurological sequelae, and reduced mortality specifically in pneumococcal meningitis 4
• The benefit was observed in high-income countries with high standards of medical care, but not in low-income settings 4

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Pathogen-Specific Definitive Therapy

Once culture and susceptibility results are available, narrow antibiotic therapy:

Streptococcus pneumoniae (Penicillin-Sensitive)

• Penicillin G 24 million units/day IV (divided every 4 hours) OR continue ceftriaxone 2g IV every 12 hours for 10-14 days 2

Streptococcus pneumoniae (Penicillin-Resistant or Unknown Susceptibility)

• Continue ceftriaxone 2g IV every 12 hours PLUS vancomycin 15-20 mg/kg IV every 8-12 hours for 10-14 days 2

Neisseria meningitidis

• Penicillin G 24 million units/day IV OR ceftriaxone 2g IV every 12 hours for 5-7 days 2
• Give a single dose of ciprofloxacin 500 mg PO for nasopharyngeal eradication before discharge 4, 2

Listeria monocytogenes

• Ampicillin 2g IV every 4 hours (12g total daily dose) for 21 days 2
• Gentamicin may be added for synergy in severe cases, though evidence is limited 2

Haemophilus influenzae

• Continue ceftriaxone or cefotaxime for 10 days 2

Pseudomonas aeruginosa

• Ceftazidime 2g IV every 8 hours PLUS tobramycin 3-5 mg/kg/day IV divided every 8 hours for 21 days 2
• If associated with neurosurgical hardware or shunt, removal is typically necessary 2

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Indications for CT Before Lumbar Puncture

Perform CT scan before lumbar puncture if any of the following are present:

• Age ≥60 years 1
• Immunocompromised state 1
• History of CNS disease (mass lesion, stroke, focal infection) 1
• New-onset seizures within 1 week 1
• Altered mental status (Glasgow Coma Scale <12) 1
• Focal neurological deficits 1
• Papilledema 1

Critical caveat: If CT is indicated, start empiric antibiotics and dexamethasone BEFORE sending the patient for imaging 1, 3. Only perform lumbar puncture after CT if there is no mass effect or elevated intracranial pressure 1.

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Prophylaxis for Close Contacts

Meningococcal Meningitis

All close contacts must receive antibiotic prophylaxis within 24 hours of case identification to prevent secondary cases and eradicate nasopharyngeal carriage. 4

• Ciprofloxacin 500 mg PO single dose (preferred for adults) 4
• Ceftriaxone 250 mg IM single dose (preferred for pregnant women and children) 4
• Rifampicin 600 mg PO every 12 hours for 2 days (alternative) 4

Close contacts include household members, child care center contacts, and anyone directly exposed to oral secretions 4. The risk of meningococcal disease is increased 400-800-fold in close contacts 4.

Pneumococcal Meningitis

• Vaccinate patients after recovery with pneumococcal vaccine to reduce recurrence risk of 1-5% 4
• Vaccination is especially important in patients with CSF leakage 4

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Adjunctive Therapies NOT Recommended

The ESCMID guideline explicitly advises against several adjunctive therapies:

• Glycerol is contraindicated in bacterial meningitis (associated with worse outcomes in adults) 4
• Therapeutic hypothermia is contraindicated (associated with higher mortality) 4
• Routine use of mannitol, acetaminophen, antiepileptic drugs, or hypertonic saline is not recommended 4
• Immunoglobulins, heparin, and activated protein C are not recommended 4

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Common Pitfalls to Avoid

• Delaying antibiotics for imaging: Never wait for CT results before starting antibiotics if bacterial meningitis is suspected 1, 2
• Inadequate Listeria coverage: Always add ampicillin for patients ≥50 years or immunocompromised 1, 2
• Insufficient antibiotic dosing: Use high-dose regimens to ensure adequate CSF penetration (ceftriaxone 2g every 12 hours, not lower doses) 2
• Neglecting blood cultures: Always obtain blood cultures before antibiotics, but never delay treatment to do so 1, 2
• Forgetting dexamethasone: Administer before or with the first antibiotic dose for maximum benefit 4, 2
• Premature discontinuation: Complete the full duration of therapy (5-21 days depending on pathogen) 2

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Duration of Antibiotic Therapy

• N. meningitidis: 5-7 days 2
• H. influenzae: 10 days 2
• S. pneumoniae: 10-14 days 4, 2
• Listeria monocytogenes: 21 days 2
• Pseudomonas aeruginosa: 21 days 2
• Unknown pathogen (culture-negative): Minimum 14 days with empiric regimen 4

The ESCMID guideline does not recommend short-course antibiotic therapy (5 days) in European settings, despite evidence from resource-limited settings, due to differences in epidemiology and comorbidities 4.