How do you work up the patient with suspected meningitis?

To Determine Diagnosis
  • Consider need for CT prior to lumbar puncture:
    • Perform to exclude mass lesion if altered consciousness, focal signs, papilledema, a recent seizure or is immunocompromised
    • Do not delay treatment for CT – take blood cultures and commence antibiotics before scanning
  • Lumbar puncture & CSF examination (if mass lesion excluded):
    • Opening pressure
    • Glucose, protein, lactate
    • Cell count
    • Gram stain
    • Bacterial culture
    • Pneumococcal and meningococcal PCR
    • Viral PCR (enteroviruses, herpes simplex viruses type 1 and 2 (HSV-1 and HSV-2) and varicella zoster virus (VZV)
  • Blood investigations:
    • Blood cultures
    • Pneumococcal and meningococcal PCR
    • Glucose
    • Lactate
    • Procalcitonin
    • Full blood count, urea, creatinine, electrolytes, liver function tests and clotting screen
    • Additional investigations to determine aetiology:
  • Throat swab for meningococcal culture
  • Stool and/or throat swabs should be tested for enterovirus by PCR
  • Selected investigations to detect source of infection:
    • Chest X-ray – pneumonia
    • Skull X-ray – fracture
    • Sinus X-ray – sinusitis
    • Petrous views – mastoiditis
To Assess for Complications
  • Assess serum electrolytes (high frequency of SIADH)