What is the recommended treatment for acute bacterial meningitis due to Pseudomonas (Pseudomonas aeruginosa)?

Treatment of Acute Bacterial Meningitis Due to Pseudomonas aeruginosa

For acute bacterial meningitis caused by Pseudomonas aeruginosa, the recommended treatment is high-dose ceftazidime (2g IV every 8 hours) combined with an aminoglycoside for the first week, followed by ceftazidime monotherapy to complete a total of 21 days of treatment.

First-line Treatment Regimen

Initial Empiric Therapy

• When Pseudomonas is suspected but not yet confirmed:
  • Ceftazidime 2g IV every 8 hours
  • PLUS an aminoglycoside (e.g., gentamicin or amikacin) for the first 7 days
  • Consider adding vancomycin if MRSA cannot be ruled out

Confirmed Pseudomonas Meningitis

• Definitive therapy:
  • Ceftazidime 2g IV every 8 hours (FDA-approved for Pseudomonas meningitis) 1
  • Continue aminoglycoside for first 7 days to prevent development of resistance 2
  • Total duration: 21 days (minimum 14 days after CSF sterilization)

Rationale for Treatment Selection

Ceftazidime is specifically indicated for central nervous system infections caused by Pseudomonas aeruginosa 1. It demonstrates superior CSF penetration compared to other cephalosporins when treating Pseudomonas meningitis 3. Studies show a 79.2% cure rate with ceftazidime for P. aeruginosa meningitis, even in patients who failed previous antibiotic regimens 2.

The addition of an aminoglycoside during the first week is recommended due to concerns about the development of resistance when ceftazidime is used as monotherapy 2. This combination approach has shown improved outcomes in clinical practice.

Monitoring and Follow-up

• CSF sterilization monitoring:

  • Repeat lumbar puncture after 48-72 hours of therapy to confirm CSF sterilization
  • If CSF remains positive after 72 hours, consider:
    1. Resistance development
    2. Need for intraventricular antibiotic administration
    3. Presence of complications (e.g., abscess)

• Clinical monitoring:

  • Daily neurological assessment
  • Temperature curve
  • Inflammatory markers (CRP, WBC count)

Special Considerations

Treatment Failures

If the patient fails to respond to intravenous therapy despite in vitro sensitivity:

• Consider intraventricular/intrathecal aminoglycoside administration via reservoir 4
• Evaluate for complications (abscess, ventriculitis)
• Reassess antibiotic susceptibility patterns

Duration of Treatment

• Minimum 21 days total therapy for Pseudomonas meningitis
• Continue treatment for at least 14 days after CSF sterilization
• For culture-negative meningitis with strong clinical suspicion, continue empiric treatment for at least 2 weeks 5

Alternative Treatment Options

If ceftazidime cannot be used (e.g., allergy, resistance):

• Meropenem 2g IV every 8 hours (alternative for ESBL-producing organisms) 6
• Ciprofloxacin may be considered as part of combination therapy, but should not be used as monotherapy due to insufficient CNS penetration and coverage 6, 4

Important Caveats

• Do not delay treatment - initiate antibiotics immediately upon suspicion of bacterial meningitis
• Never use monotherapy with aminoglycosides as they have poor CSF penetration when administered systemically 4
• Avoid rifampicin monotherapy to prevent development of resistance 5
• Therapeutic hypothermia and glycerol are contraindicated in bacterial meningitis 5
• Dexamethasone (10mg IV every 6 hours for 4 days) should be started with or before the first antibiotic dose, though evidence for benefit specifically in Pseudomonas meningitis is limited 6

By following this treatment approach, you maximize the chances of successful eradication of Pseudomonas aeruginosa from the CNS while minimizing the risk of treatment failure and development of resistance.