CNS infections and their treatment

Table of Contents

Central nervous system (CNS) infections include a spectrum of diseases such as meningitis, encephalitis, brain abscess, and healthcare-associated ventriculitis/meningitis. These conditions are associated with significant morbidity and mortality, requiring rapid diagnosis and prompt, targeted intervention.

I. Types of CNS Infections

Infection Type	Most Common Causes	Key Features/Notes
Meningitis	Bacterial: S. pneumoniae, N. meningitidis, H. influenzae, L. monocytogenes. Viral: enteroviruses, HSV, VZV, HIV	Neck stiffness, photophobia, fever, headache, altered mental status
Encephalitis	HSV-1, arboviruses (West Nile, Japanese, Tick-borne), VZV, CMV, EBV, autoimmune, post-infectious	Confusion, seizures, altered consciousness, focal neurological deficits
Brain Abscess	Streptococci, S. aureus, anaerobes, Gram-negatives	Focal signs, increased intracranial pressure, less meningeal signs
Healthcare-associated ventriculitis/meningitis	Coagulase-negative staphylococci, Gram-negatives	Related to shunts, catheters, neurosurgery

II. Diagnosis

Clinical assessment: History and physical (fever, neurological signs, travel exposure)
Neuroimaging (CT/MRI): BEFORE lumbar puncture (LP) in suspected increased ICP or focal signs
Lumbar puncture: Essential for CSF analysis (cell count, protein, glucose, Gram stain/culture, PCR for viral pathogens)
Blood cultures
Rapid Diagnostics: PCR for HSV, VZV, enteroviruses; galactomannan and β-D-glucan for fungal CNS infections
Ancillary labs: CBC, renal/liver function, glucose

III. Empirical Therapy: Start Immediately (Do NOT delay for imaging in absence of contraindications)

A. Bacterial Meningitis

Age Group / Risk Factors	Empirical Antibiotics	Notes
Adults, community-acquired	Ceftriaxone + vancomycin	Add ampicillin if >50 years, immunosuppressed: cover L. monocytogenes
Neonates, infants	Ampicillin + gentamicin/cefotaxime	Cover GBS, E. coli, L. monocytogenes
Immunosuppressed/pregnant	Ampicillin + ceftriaxone + vancomycin	Add acyclovir if HSV possible
Shunt/neurosurgical, healthcare-assoc	Meropenem + vancomycin (± ceftazidime)	Cover MRSA, Pseudomonas, ESBL

Adjunctive Dexamethasone: For adults/children with suspected S. pneumoniae meningitis, started with or before first antibiotic dose.

B. Viral CNS Infections

Encephalitis (HSV, VZV): High-dose IV acyclovir
CMV: IV ganciclovir or foscarnet
Supportive care: ICU monitoring, control of seizures, intracranial pressure
Autoimmune/post-infectious: Immunomodulatory therapy (steroids, IVIG, plasma exchange) when indicated.

C. Fungal CNS Infections

Infection	First-Line Agents	Notes
Cryptococcal meningitis	Amphotericin B + flucytosine induction, then fluconazole maintenance	HIV, transplants; prolonged therapy
Candida CNS	Amphotericin B ± flucytosine/echinocandins	High mortality; remove infected devices
Aspergillus	Voriconazole	Immunosuppressed hosts

D. Brain Abscess

Empiric: Ceftriaxone + metronidazole ± vancomycin
Surgery for drainage often required
Tailor therapy to microbiology.

IV. Duration of Therapy

Infection Type	Typical Duration
Bacterial Meningitis	7–21 days (pathogen-specific)
HSV Encephalitis	≥14–21 days
Brain Abscess	4–8 weeks post-surgical drainage
Cryptococcal meningitis	Induction (2 weeks), consolidation (8 weeks), maintenance (≥6 months)

V. Prevention and Adjuncts

Vaccination: Hib, pneumococcus, meningococcus, mumps, measles, VZV vaccines
Chemoprophylaxis: Close contacts of meningococcal cases (rifampin, ciprofloxacin, ceftriaxone)
Supportive measures: Airway, seizure control, fluid status, ICP management, rehabilitation
Monitor for complications: Hearing loss, neurologic sequelae, hydrocephalus

VI. Special Cases

Patient Group	Key Pathogens / Considerations
Neonates	GBS, E. coli, Listeria, HSV
Elderly	S. pneumoniae, L. monocytogenes, Gram-negatives
Immunocompromised	CMV, HSV, JC virus (PML), fungi
Returning travelers	Arboviruses (WNV, JEV), malaria, TB

VII. References

Shrestha J. CNS Infections. StatPearls [Internet]. 2023.
WHO guidelines on meningitis diagnosis, treatment and care. Geneva: World Health Organization; 2025 Apr 9.
Dagra A, et al. Encephalitis and Meningitis: Indications for Intervention. JClinical.org. 2023 Apr 25.
Mayo Clinic. Encephalitis—Diagnosis and treatment. 2024 May 15.
Shin SH, Kim KS. Treatment of Bacterial Meningitis: An Update. Expert Opin Pharmacother. 2012 Oct;13(15):2189-206.
Sigfrid L, et al. Clinical guidelines for community-acquired CNS infections in Europe: A systematic review. JAC. 2019 Sep 5.
CDC. Tick-borne encephalitis—Treatment and prevention. 2024 May 13.
Hart CA. Management of bacterial meningitis. J Infect. 1993.

How to cite this page - Vancouver Style

Mentor, Pharmacology. CNS infections and their treatment. Pharmacology Mentor. Available from: https://pharmacologymentor.com/cns-infections-and-their-treatment/. Accessed on January 27, 2026 at 19:34.

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