What is the recommended treatment for suspected meningitis?

Recommended Treatment for Suspected Meningitis

All patients with suspected bacterial meningitis should receive immediate empiric antibiotic therapy with ceftriaxone 2g IV every 12 hours (or cefotaxime 2g IV every 6 hours) plus vancomycin 15-20 mg/kg IV every 8-12 hours, with antibiotics administered within 1 hour of presentation. 1, 2

Initial Empiric Antibiotic Regimen

Standard Adult Therapy (<60 years, immunocompetent)

• Ceftriaxone 2g IV every 12 hours OR Cefotaxime 2g IV every 6 hours 1, 2
• PLUS Vancomycin 15-20 mg/kg IV every 8-12 hours (target trough 15-20 μg/mL) 1, 2, 3

The combination of a third-generation cephalosporin with vancomycin provides optimal coverage for the most common pathogens (Streptococcus pneumoniae and Neisseria meningitidis) while addressing concerns about cephalosporin-resistant pneumococci. 1, 2 Third-generation cephalosporins have excellent bactericidal activity against pneumococci and meningococci with superior CSF penetration. 1, 4 Vancomycin is added empirically because experimental models demonstrate synergy with ceftriaxone against resistant pneumococcal strains. 5, 3

Modified Regimens for High-Risk Populations

For patients ≥60 years of age:

• Add Ampicillin 2g IV every 4 hours to the standard regimen 1, 2
• This provides coverage for Listeria monocytogenes, which is more common in older adults 1, 2

For immunocompromised patients (including diabetics, alcohol misuse, cancer, immunosuppressive drugs):

• Add Ampicillin 2g IV every 4 hours to the standard regimen 1, 2
• These patients have increased risk of Listeria infection 2

For patients with recent travel to areas with penicillin-resistant pneumococci (within last 6 months):

• Continue the standard ceftriaxone/cefotaxime plus vancomycin regimen 1
• Alternative: Add Rifampicin 600mg IV/PO every 12 hours if vancomycin cannot be used 1

Penicillin Allergy

For clear history of anaphylaxis to penicillins or cephalosporins:

• Chloramphenicol 25 mg/kg IV every 6 hours 1

Critical Timing Considerations

Time from hospital entry to antibiotic administration must not exceed 1 hour. 2, 6 This is paramount because delays in treatment are strongly associated with increased mortality and poor neurological outcomes. 2

Key Procedural Points:

• Obtain blood cultures before antibiotics, but do NOT delay treatment 2, 6
• If lumbar puncture is delayed (e.g., for CT imaging), start empiric antibiotics immediately 2, 6
• Do not wait for CSF results to initiate therapy 1, 2

Pathogen-Directed Therapy (Once Organism Identified)

Streptococcus pneumoniae

• If penicillin-sensitive (MIC ≤0.06 mg/L): Switch to benzylpenicillin 2.4g IV every 4 hours OR continue ceftriaxone/cefotaxime 1, 2
• If penicillin-resistant but cephalosporin-sensitive: Continue ceftriaxone or cefotaxime 1
• If both penicillin and cephalosporin-resistant: Continue ceftriaxone/cefotaxime PLUS vancomycin PLUS rifampicin 600mg every 12 hours 1
• Duration: 10 days if recovered by day 10; extend to 14 days if not fully recovered or if resistant organism 1, 2

Neisseria meningitidis

• Continue ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 2
• Alternative: Benzylpenicillin 2.4g IV every 4 hours 2
• Duration: 5-7 days with good clinical response 2, 6

Listeria monocytogenes

• Amoxicillin 2g IV every 4 hours 2
• Duration: 21 days 2

Haemophilus influenzae

• Continue ceftriaxone or cefotaxime 2, 6
• Duration: 10 days 2, 6

Common Pitfalls to Avoid

Critical errors that worsen outcomes:

1. Delaying antibiotics for imaging or lumbar puncture - This is the most dangerous error; antibiotics must be given within 1 hour even if LP is delayed 2, 6

2. Inadequate Listeria coverage in high-risk patients - Failing to add ampicillin in patients ≥60 years or immunocompromised leaves a critical gap 1, 2

3. Omitting vancomycin from empiric therapy - Despite decreased prevalence of resistant pneumococci, vancomycin should still be included empirically given the high mortality risk 3

4. Failing to obtain blood cultures before antibiotics - While this should not delay treatment, blood cultures are essential for pathogen identification 2, 6

5. Not considering recent travel history - Patients returning from areas with high pneumococcal resistance require enhanced coverage 1

6. Insufficient dosing - Standard doses are required to achieve adequate CSF penetration; lower doses are inadequate 2

Special Administration Considerations

• Ceftriaxone must NOT be mixed with calcium-containing solutions due to precipitation risk 7
• In neonates, administer IV doses over 60 minutes to reduce bilirubin encephalopathy risk 6, 7
• In adults, infuse over 30 minutes 7
• Monitor vancomycin trough levels to maintain therapeutic concentrations of 15-20 μg/mL 6