What is the recommended treatment for suspected bacterial meningitis?

Treatment for Suspected Bacterial Meningitis

For suspected bacterial meningitis, immediate empiric antimicrobial therapy should be initiated with vancomycin plus either ceftriaxone or cefotaxime, along with adjunctive dexamethasone started before or simultaneously with antibiotics. 1, 2

Initial Assessment and Management

Immediate Actions

1. Obtain blood cultures within 1 hour of hospital arrival 1
2. Assess Glasgow Coma Scale (GCS) score 1
3. Perform lumbar puncture (LP) within 1 hour if safe to do so 1
4. Start empiric antimicrobial therapy immediately after LP (or after blood cultures if LP is delayed) 2, 1
5. Administer dexamethasone before or with first antimicrobial dose 2, 1

Contraindications to Immediate LP

• Severely decreased consciousness
• New onset focal neurological signs
• Epileptic seizures 3

If any of these are present, obtain neuroimaging before LP, but do not delay antimicrobial therapy 2, 3

Empiric Antimicrobial Therapy

Standard Adult Regimen

• Vancomycin plus either:
  • Ceftriaxone 2g IV every 12 hours, or
  • Cefotaxime 2g IV every 6 hours 1, 2

Age-Specific Considerations

• Adults <60 years: Ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours
• Adults ≥60 years: Add amoxicillin 2g IV every 4 hours to the above regimen 1

Special Situations

• For penicillin-resistant pneumococci: Add rifampicin 600mg twice daily 2
• For nosocomial meningitis: Consider meropenem (indicated for bacterial meningitis caused by H. influenzae, N. meningitidis, and penicillin-susceptible S. pneumoniae) 4

Adjunctive Therapy

Dexamethasone

• Dose: 10mg IV every 6 hours 2, 1
• Duration:
  • If pneumococcal meningitis is confirmed: Continue for 4 days
  • If another cause is confirmed: Discontinue 2
• Timing: Start before or simultaneously with antibiotics, up to 12 hours after first antibiotic dose 2

Not Recommended

• Glycerol is not recommended as adjunctive therapy 2
• Therapeutic hypothermia is not recommended 2

Monitoring and Critical Care Considerations

Indications for ICU Admission

• GCS ≤12 or drop of >2 points
• Rapidly evolving rash
• Cardiovascular instability
• Acid/base disturbance
• Hypoxia or respiratory compromise
• Frequent seizures
• Altered mental state 2, 1

Supportive Care

• Maintain mean arterial pressure ≥65 mmHg
• Target euvolemia (avoid fluid restriction)
• Consider intubation for GCS <12 1, 2

Important Clinical Considerations

Timing of Treatment

• Bacterial meningitis is a neurologic emergency 5
• Start antibiotics as soon as possible after diagnosis is considered likely 2
• Do not delay antibiotics for imaging or LP 2, 3

Diagnostic Yield

• CSF culture positivity decreases significantly with time after antibiotic administration:
  • 73% positive if LP performed within 4 hours of antibiotics
  • 11% positive if LP performed after 4 hours
  • 0% positive if LP performed after 8 hours 6

Common Pitfalls to Avoid

1. Unnecessary CT scans delaying LP and treatment 6
2. Delaying antibiotics while awaiting neuroimaging 2, 3
3. Failing to recognize meningococcal sepsis, which can maintain blood pressure until late in disease before rapid deterioration 1
4. Not considering antimicrobial resistance when selecting initial therapy 2, 1

By following this algorithmic approach to suspected bacterial meningitis, you can optimize patient outcomes by ensuring prompt diagnosis and appropriate treatment.