Treatment of Haemophilus influenzae Meningitis
For confirmed H. influenzae meningitis, treat with ceftriaxone 2 grams IV every 12 hours OR cefotaxime 2 grams IV every 6 hours for 10 days. 1
Primary Treatment Regimen
The UK Joint Specialist Societies guideline provides the definitive treatment approach for H. influenzae meningitis in adults:
- Ceftriaxone 2 grams IV every 12 hours for 10 days 1
- Alternative: Cefotaxime 2 grams IV every 6 hours for 10 days 1
- Second-line alternative: Moxifloxacin 400 mg once daily for 10 days 1
The twice-daily dosing of ceftriaxone is critical for achieving adequate CSF concentrations throughout the dosing interval, particularly in the first 24-48 hours when rapid bacterial clearance is essential. 2
Pediatric Dosing (≥3 months of age)
For children with H. influenzae meningitis:
- Meropenem 40 mg/kg IV every 8 hours (maximum 2 grams per dose) is FDA-approved specifically for H. influenzae meningitis in pediatric patients 3
- Ceftriaxone 80-100 mg/kg IV once daily has demonstrated efficacy, with CSF concentrations 10-100 fold higher than the MIC even 24 hours after dosing 4, 5
- Treatment duration: 10 days 1
Treatment Duration Considerations
- Standard duration: 10 days if clinically stable 1, 6
- Treatment may need extension beyond 10 days if the patient is not responding adequately 1
- CSF should be sterile within 24-48 hours of initiating appropriate therapy 4, 5
Monitoring and Adjustment
Reassess at day 6-10 if persistent symptoms:
- Verify adequate dosing and drug levels 6
- Consider repeat lumbar puncture to confirm CSF sterilization 6
- Evaluate for complications (subdural effusion, cerebral abscess) 3
- Ensure antimicrobial susceptibility testing has been performed 6
Critical Pitfalls to Avoid
- Do not use inadequate treatment duration - gram-negative organisms like H. influenzae require the full 10-day course 6
- Do not fail to adjust therapy based on susceptibility testing if resistance patterns emerge 6
- Do not use once-daily ceftriaxone dosing in adults - twice-daily dosing (2g every 12 hours) is required for meningitis to maintain adequate CSF concentrations 1, 2
- Do not discontinue therapy prematurely even if the patient improves rapidly - complete the full 10-day course 1
Special Clinical Scenarios
If beta-lactamase producing H. influenzae is suspected or confirmed:
- Third-generation cephalosporins (ceftriaxone/cefotaxime) remain highly effective as they are resistant to beta-lactamase 7
- No dosing adjustment is required 1
For patients with difficult IV access:
- Intramuscular ceftriaxone can be considered in pediatric patients with adequate peripheral perfusion, though IV route is strongly preferred for meningitis 8
Outpatient therapy consideration:
- Once clinically stable and afebrile after ≥5 days of inpatient therapy, outpatient IV ceftriaxone may be considered with appropriate monitoring 1