Treatment of Pseudomonas Meningitis
For Pseudomonas aeruginosa meningitis, ceftazidime is the drug of choice, typically given at 2g IV every 8 hours (or 50 mg/kg every 8 hours in children), and should be combined with an aminoglycoside (tobramycin or gentamicin) for at least the first week of therapy, with treatment duration of 21 days. 1, 2
Antibiotic Selection and Rationale
Primary Therapy: Ceftazidime
- Ceftazidime is the only third-generation cephalosporin with adequate CSF penetration and reliable activity against Pseudomonas aeruginosa. 2, 3, 4
- The FDA label specifically indicates ceftazidime for CNS infections including meningitis caused by Pseudomonas aeruginosa, based on successful clinical use. 2
- Adult dosing: 2g IV every 8 hours 2
- Pediatric dosing: 50 mg/kg IV every 8 hours (maximum 6g/day) 2
Combination Therapy with Aminoglycosides
- An aminoglycoside (tobramycin or gentamicin) should be added to ceftazidime for at least the first 7 days to prevent resistance development. 5
- Tobramycin is FDA-approved for CNS infections (meningitis) and has documented efficacy against Pseudomonas. 6
- Standard IV dosing: 3-5 mg/kg/day divided every 8 hours 1
- Consider intraventricular aminoglycoside administration (4-8 mg daily for adults, 1-2 mg daily for infants/children) in cases of treatment failure or ventriculitis. 1, 7
Treatment Duration
- Pseudomonas meningitis requires 21 days of IV antibiotic therapy. 1
- This extended duration is necessary due to the organism's virulence and propensity for treatment failure. 1
- CSF sterilization typically occurs within 48 hours to 12 days, but the full 21-day course must be completed. 8
Clinical Evidence and Success Rates
- Ceftazidime monotherapy achieved cure rates of 79.2% in adults with Pseudomonas meningitis, though many had failed prior regimens. 5
- In pediatric studies, ceftazidime (with or without concurrent aminoglycosides) achieved clinical cure in 7 of 10 patients and bacteriologic cure in 9 of 10 patients. 8
- Combined intraventricular and IV tobramycin with ceftazidime has successfully treated post-shunt Pseudomonas ventriculitis. 7
Critical Pitfalls to Avoid
Inadequate Drug Selection
- Do NOT use cefotaxime or ceftriaxone for Pseudomonas meningitis—these agents lack adequate anti-pseudomonal activity. 3, 4
- First- and second-generation cephalosporins are completely ineffective and should never be used. 3, 4
Monotherapy Concerns
- Using ceftazidime alone risks resistance development during therapy, particularly in the first week. 5
- While monotherapy can succeed, combination therapy with an aminoglycoside for at least 7 days is prudent. 5
Inadequate Treatment Duration
- Do NOT shorten the 21-day course even if CSF sterilizes early—premature discontinuation leads to relapse. 1
Shunt-Related Infections
- In patients with CSF shunt infections, the shunt must typically be removed for cure. 1
- If the shunt cannot be removed, consider adding rifampin to the regimen (though this is more relevant for staphylococcal infections). 1
Monitoring Requirements
- Obtain baseline and serial CSF cultures to document sterilization. 1
- Monitor aminoglycoside serum levels to maintain therapeutic concentrations while avoiding nephrotoxicity and ototoxicity. 6
- Assess renal function regularly during aminoglycoside therapy. 6
- Clinical improvement should be evident within 48-72 hours; lack of response warrants reassessment. 8
Special Considerations
Adjunctive Dexamethasone
- Dexamethasone should be discontinued once Pseudomonas is identified, as it is only beneficial for pneumococcal and H. influenzae meningitis. 1