Central Nervous System Infections

Bacterial Meningitis

Clinical Presentation

• Fever, headache, vomiting
• Photophobia, neck stiffness
• Altered mental status
• Seizures
• Rash (e.g. meningococcal)

Diagnostic Workup

• Full clinical examination
• Blood cultures
• Lumbar puncture (unless contraindicated)
  • Send CSF for:
    • Cell count
    • Glucose
    • Protein
    • Gram stain
    • Bacterial culture
    • PCR for specific organisms
    • Cryptococcal antigen if HIV-positive

Empirical Antibiotic Therapy (Adults)

✅ HTML Table – Empiric Treatment‍


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• Add dexamethasone 10 mg IV 6-hourly x 4 days if S. pneumoniae is suspected (before/with antibiotics).
• Duration:
  • Meningococcus: 5–7 days
  • Pneumococcus: 10–14 days
  • Listeria: ≥21 days

Neonatal Meningitis

Empiric Therapy

• Ampicillin + Gentamicin
  • Add Cefotaxime if Gram-negative bacilli or complications suspected.

Tuberculous Meningitis

Presentation

• Subacute onset of headache, fever, confusion
• Cranial nerve palsies
• Hydrocephalus

Diagnosis

• CSF:
  • Lymphocytic pleocytosis
  • High protein, low glucose
• GeneXpert Ultra, AFB smear, TB culture

Treatment

• RIPE (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol) for 2 months
• Followed by Rifampicin + Isoniazid for 7–10 months
• Add prednisone 60 mg PO for 6–8 weeks, then taper

Viral Meningitis

• Most commonly enteroviruses
• Usually self-limiting
• Treatment supportive only

Herpes Simplex Virus (HSV) Encephalitis

Presentation

• Fever, headache
• Behavioural changes, focal signs
• Seizures, altered consciousness

Diagnosis

• CSF: lymphocytes, elevated protein, normal glucose
• PCR for HSV-1/HSV-2
• Brain MRI: temporal lobe involvement

Treatment

• Acyclovir 10 mg/kg IV 8-hourly × 14–21 days
• Adjust dose for renal function

Cryptococcal Meningitis (HIV-associated)

Symptoms

• Headache, fever, nausea
• Altered mental status
• Increased intracranial pressure

Diagnosis

• Cryptococcal antigen (CrAg) in CSF and serum
• CSF opening pressure >25 cm H₂O

Treatment (WHO 2022)

1. Induction (2 weeks):
   • Liposomal amphotericin B 10 mg/kg IV single dose
   • PLUS
   • Flucytosine 100 mg/kg/day PO ÷ q6h for 14 days
2. Consolidation (8 weeks):
   • Fluconazole 800 mg/day PO
3. Maintenance:
   • Fluconazole 200 mg/day PO until immune reconstitution

Neurosyphilis

• Occurs at any stage of syphilis
• CSF VDRL is diagnostic

Treatment

• Benzylpenicillin 4 million units IV every 4h for 14 days
• Alternatives:
  • Procaine penicillin 2.4 MU IM daily + Probenecid PO x 14 days
  • Ceftriaxone 2 g IV daily x 14 days (if penicillin-allergic)

Neurocysticercosis

Caused by:

• Larval form of Taenia solium

Symptoms:

• Seizures
• Headaches
• Raised intracranial pressure

Diagnosis:

• CT/MRI: cysts or calcifications
• Serology supportive

Treatment:

• Albendazole 15 mg/kg/day (max 800 mg) in 2 divided doses × 7–14 days
• Add corticosteroids to reduce inflammatory response
• Seizure prophylaxis as needed