Treatment of Meningococcal Encephalitis in Immunocompromised Patients
Immunocompromised patients with suspected meningococcal encephalitis should receive immediate empiric treatment with ceftriaxone 2g IV every 12 hours plus vancomycin 15-20 mg/kg IV every 8-12 hours, with dexamethasone 10mg IV every 6 hours administered before or simultaneously with the first antibiotic dose. 1
Critical Initial Actions (Within 1 Hour)
- Obtain blood cultures immediately before antibiotics, but do not delay antibiotic administration beyond 1 hour of presentation 1
- Administer dexamethasone 10mg IV every 6 hours immediately before or simultaneously with the first antibiotic dose 1, 2
- Consider CT head scan before lumbar puncture in severely immunocompromised patients, as they may have lesions without focal neurological signs or papilloedema 3
- Start empiric antibiotics after blood cultures even if lumbar puncture is delayed 1
Empiric Antibiotic Regimen for Immunocompromised Patients
For patients ≥60 years or immunocompromised:
- Ceftriaxone 2g IV every 12 hours (or cefotaxime 2g IV every 6 hours) 1
- PLUS Vancomycin 15-20 mg/kg IV every 8-12 hours 1
- PLUS Amoxicillin 2g IV every 4 hours (for Listeria coverage, which is critical in immunocompromised patients) 1
The addition of amoxicillin is essential because immunocompromised patients are at significantly higher risk for Listeria monocytogenes, which is not covered by ceftriaxone alone 3.
Adjunctive Dexamethasone Therapy
- Administer dexamethasone 10mg IV every 6 hours for 4 days 1, 2
- Timing is critical: give 10-20 minutes before or simultaneously with first antibiotic dose 2
- If antibiotics already started, dexamethasone can still be initiated up to 12 hours after first antibiotic dose 2
- Continue full 4-day course if bacterial meningitis confirmed; discontinue if ruled out 2
Diagnostic Workup Specific to Immunocompromised Patients
Immunocompromised patients require broader microbiological investigation because they are vulnerable to atypical pathogens:
- CSF PCR for HSV 1 & 2, VZV, and enteroviruses 3
- CSF PCR for EBV and CMV 3
- CSF acid-fast bacillus staining and culture for M. tuberculosis 3
- CSF and blood culture for Listeria monocytogenes 3
- Indian ink staining and/or cryptococcal antigen (CRAG) testing for Cryptococcus neoformans 3
- Antibody testing and if positive CSF PCR for Toxoplasma gondii 3
- Consider CSF PCR for HHV-6 and 7, JC/BK virus 3
Critical Pitfalls to Avoid
Do not delay antibiotics for imaging or lumbar puncture results - mortality increases significantly with treatment delays 1, 4
Do not assume normal CSF cell count rules out infection - immunocompromised patients frequently have acellular CSF despite active CNS infection, so microbiological investigations must be performed regardless of cell count 3
Do not omit Listeria coverage - failing to add amoxicillin/ampicillin in patients >50 years or immunocompromised is a common and potentially fatal error 1
Do not give dexamethasone after 12 hours of antibiotic initiation - this represents inappropriate steroid exposure without benefit 2
Special Considerations for Immunocompromised Patients
- Presentations are often subtle and subacute rather than acute - consider encephalitis even with prolonged history, subtle features, or absence of fever 3
- MRI is the imaging modality of choice (not CT) because immunocompromised patients are vulnerable to broader range of encephalitides including progressive multifocal leukoencephalopathy 3
- Patients with HIV should be treated in an HIV center 3
- For confirmed HSV encephalitis in immunocompromised patients, treat with IV acyclovir 10mg/kg three times daily for at least 21 days (longer than immunocompetent patients), then reassess with CSF PCR 3
ICU Transfer Criteria
Transfer to ICU if patient has: 1
- Glasgow Coma Scale ≤12 or drop >2 points
- Cardiovascular instability or sepsis
- Rapidly evolving rash
- Frequent seizures or altered mental state requiring specific organ support