Antimicrobial Stewardship (AMS)

• Local ceftriaxone resistance in S. pneumoniae is estimated to be approximately 1%.

Last reviewed August 2024

• Collect 2 sets of blood cultures
• Head CT prior to lumbar puncture if focal neurological signs, papilledema, altered mentation, new onset seizures, impaired cellular immunity
• Lumbar puncture
• Defer if high bleeding risk (INR greater than 1.4, platelets less than 50 x 10⁹/L ) 
  • Cell count, glucose, protein, Gram stain, culture, opening pressure
• Negative Gram stain does not exclude bacterial meningitis: sensitivity 60-90%, lower for Listeria (less than 50%)
  • Typical CSF findings: elevated WBC (predominately neutrophils; may be predominantly lymphocytes and/or monocytes with Listeria), elevated protein, low glucose
• Predictors of bacterial infection: WBC greater than or equal to 500 x 10⁶/L, CSF-blood glucose ratio less than or equal to 0.4
  • CSF PCR if suspect viral causes (e.g., Enteroviruses)

Last reviewed August 2024

• Delay of antibiotics increases mortality. Do not delay antibiotics if neuroimaging and/or LP is delayed.
• Initiate droplet and contact precautions and notify Infection Prevention and Control
• Contact Public Health
• Repeat LP if poor clinical response after 48 hours OR resistant S. pneumoniae confirmed 

Last reviewed August 2024

• Dexamethasone 10 mg IV q6h should be started with or immediately before the FIRST dose of antibiotic and continued for 4 days if the causative agent is found to be S. pneumoniae or Haemophilus influenzae.  
• If a pathogen other than S. pneumoniae or Haemophilus influenzae is present, consider stopping dexamethasone.
• Ceftriaxone 2 g IV q12h + vancomycin 25 mg/kg total body weight (TBW) IV loading dose followed by 15 mg/kg IV q8-12h (adjust for renal function)
• Vancomycin should be discontinued for S. pneumoniae if susceptibility to ceftriaxone is confirmed (using CNS minimum inhibitory concentration (MIC) breakpoints). 
• Add ampicillin 2 g IV q4h (adjust for renal function) for Listeria coverage if age greater than 50 or risk factors (excessive alcohol consumption, immunocompromised, pregnant).

Last reviewed August 2024

• For a non-IgE mediated hypersensitivity (e.g., anaphylaxis) to penicillins, ceftiraxone can be used.
• If a third-generation cephalosporin is contraindicated, use meropenem 2 g IV Q8H (adjust for renal function).
• In the case of vancomycin allergy, use meropenem 2 g IV Q8H (adjust for renal function).
• The above recommendations are intended to prevent delay of the first doses of therapy and an Infectious Disease consultation is recommended.

Last reviewed August 2024

• Neisseria meningitidis 7 days
• Haemophilus influenzae 7 days
• Streptococcus pneumoniae 10–14 days
• Listeria monocytogenes 21 days or more

Last reviewed August 2024

• Immunocompromised (steroids, transplant patients, those with HIV) may may be at risk for fungal meningitis (e.g., Cryptococcus)
• For S. pneumoniae CNS infections, the minimum inhibitory concentration (MIC) breakpoints for penicillin and ceftriaxone differ from non-CNS infections. Consult microbiology for interpretation of susceptibility results if necessary.

Last reviewed August 2024

1. Tunkel AR, Hartman BJ, Kaplan SL, Kaufman BA, Roos KL, Scheld WM, Whitley RJ. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis. 2004;39(9):1267-84.

2. Tunkel AR, van de Beek D, Scheld WM. Acute meningitis. [edited by] John E. Bennett, Raphael Dolin, Martin J. Blaser. Mandell, Douglas, And Bennett's Principles and Practice of Infectious Diseases. Philadelphia, PA :Elsevier/Saunders, 2015. Print.

3. Straus SE, Thorpe KE, Holroyd-Leduc J.How do I perform a lumbar puncture and analyze the results to diagnose bacterial meningitis? JAMA. 2006 Oct 25;296(16):2012-22.

4. Brouwer MC, McIntyre P, Prasad K, van de Beek D. Corticosteroids for acute bacterial meningitis. Cochrane Database Syst Rev. 2015 Sep 12;(9):CD004405.

Last reviewed August 2024

• No cause in up to 60% of cases
• HSV-1 is most common and requires emergent treatment
• Others: VZV, HIV, Jamestown Canyon Virus, Snowshoe Hare Virus, Influenza, Rabies
• Bacteria: Lyme, Syphilis, Bartonella, Anaplasma, Q fever (Coxiella burnetti)
• Fungi: Cryptococcus neoformans

Last reviewed July 2025

• Differential Diagnosis
  • Infectious
    • Meningitis (See Meningitis Handbook Chapter)
    • Focal suppurative infections (brain abscesses, subdural or epidermal empyema, cerebral venous sinus thrombophlebitis)
    • Creutzfeldt-Jakob disease
  • Many non-infectious causes including inflammatory (acute disseminated encephalomyelitis), paraneoplastic and encephalopathic conditions (metabolic, toxins, drug induced)
• Clinical Presentation
  • Altered level of consciousness including drowsiness, confusion, stupor, coma
  • Fever, headache, photophobia, phonophobia, seizure, hallucinations, focal neurologic deficits
  • Nuchal rigidity may be present if concomitant meningitis
• Diagnostic Work-Up
  • In addition to routine history, consider epidemiology risks that may guide specific investigations: travel, occupation, hobbies, seasonality (tick, mosquito exposures), immunization status
  • CSF analysis
    • Opening pressure, cell count and differential, protein, glucose, Gram stain, bacterial cultures, viral PCR (HSV, VZV, enteroviruses)
    • Caution: HSV PCR can be falsely negative early in disease. If syndrome is concerning for HSV encephalitis, continue treatment and repeat LP in 72 hours
    • Viral encephalitis: pleocytosis (lymphocytic predominance), normal glucose, elevated protein
  • Consider HIV, Lyme, syphilis, cryptococcal antigen
  • MRI: temporal lobe enhancement is concerning for HSV
  • EEG: Viral encephalitis: high amplitude slow waves (delta and theta slowing), occasional lateralizing periodic discharges

Last reviewed July 2025

• Empiric high dose acyclovir is recommended immediately. Delay in therapy increases mortality. Do not delay acyclovir while awaiting neuroimaging and/or LP is delayed.

Last reviewed July 2025

• Acyclovir 10-15 mg/kg IV q8h if creatinine clearance is greater than 50 mL/minute
• Dose adjustment required for renal dysfunction.
  • See Firstline Acyclovir | Nova Scotia Health | Firstline

Last reviewed July 2025

• 14-21 days

Last reviewed July 2025

• Treatment duration may vary in the setting of immunocompromise; ID consult recommended
• Adverse reaction considerations: dose-related AKI can occur, most commonly from crystallization of acyclovir
• Monitor serum creatinine, hydration status and neurotoxicity

Last reviewed July 2025

Last reviewed July 2025