What is the evaluation and treatment approach for meningitis?

Evaluation and Treatment of Acute Meningitis

Immediate Priorities: The First Hour

All patients with suspected meningitis require immediate stabilization of airway, breathing, and circulation, followed by blood cultures and empiric antibiotics within 1 hour of hospital arrival, with lumbar puncture performed urgently unless contraindicated. 1

Initial Assessment and Triage

• Document Glasgow Coma Scale score immediately upon arrival for prognostic value and to monitor deterioration 1
• Calculate National Early Warning Score: aggregate score ≥5-6 requires urgent senior clinician review; score ≥7 requires critical care assessment 1
• Record presence or absence of rash, fever, headache, altered mental status, neck stiffness, seizures, and any signs of shock (hypotension, poor capillary refill, cold extremities) 1
• Do not rely on Kernig's or Brudzinski's signs for diagnosis as they have variable sensitivity and specificity 1, 2
• Senior consultant review should occur much earlier than the standard 14-hour timeframe, as patients can deteriorate rapidly 1

Critical Care Criteria

Transfer to critical care is indicated for 1:

• Rapidly evolving rash
• GCS ≤12 (or drop of >2 points)
• Uncontrolled seizures
• Evidence of severe sepsis or septic shock
• Need for organ support or hemodynamic monitoring

Intubation should be strongly considered for GCS <12 1

Diagnostic Approach

Indications for CT Before Lumbar Puncture

Perform cranial imaging before LP only if 1:

• GCS ≤12 (though LP may be safe at levels below this)
• Focal neurological signs
• Papilloedema present
• Continuous or uncontrolled seizures
• Severe immunocompromised state

Critical pitfall: Inability to visualize the fundus is NOT a contraindication to LP, especially with short symptom duration 1

Lumbar Puncture Timing

For patients with suspected meningitis WITHOUT shock or severe sepsis 1:

• Perform LP within 1 hour of hospital arrival if safe
• Start treatment immediately after LP (within first hour)
• If LP cannot be performed within 1 hour, start antibiotics immediately after blood cultures and perform LP as soon as possible thereafter

For patients with predominantly sepsis or rapidly evolving rash 1:

• Give antibiotics immediately after blood cultures
• Start fluid resuscitation with 500 mL crystalloid bolus
• Follow Surviving Sepsis guidelines
• Do NOT perform LP at this time

CSF Interpretation

Best diagnostic parameter: CSF leukocyte count (area under curve 0.95) 1, 3

Typical bacterial meningitis findings 3:

• WBC count: 1,000-5,000 cells/mm³ (range 100-110,000)
• Neutrophil predominance: 80-95%
• CSF glucose <40 mg/dL (in 50-60% of cases)
• CSF:serum glucose ratio <0.4
• Elevated protein

Microbiological Confirmation

• CSF Gram stain: 60-90% sensitivity, 97% specificity (correlates with bacterial concentration) 3
• CSF culture: Positive in 70-85% of untreated patients 3
• CSF PCR: 87-100% sensitivity, 98-100% specificity; remains positive even after antibiotic administration 4
• Blood cultures should be obtained within 1 hour of arrival 1

Partially Treated Meningitis

Critical consideration: Antibiotic pretreatment significantly alters diagnostic yield 4:

• Gram stain sensitivity decreases by ~20%
• CSF cultures may sterilize within 2 hours for meningococci, 4 hours for pneumococci
• CSF WBC, glucose, and protein remain abnormal and reliable
• CSF PCR remains highly sensitive and should be utilized 4

Common pitfall: Do not assume viral meningitis based solely on lymphocytic predominance in CSF, as partially treated bacterial meningitis can present this way 4

Empiric Antibiotic Treatment

Treatment Must Begin Within 1 Hour

Antibiotics should be administered within 1 hour of hospital arrival, regardless of whether CT or LP has been performed 1. Delays in antibiotic administration increase mortality 1.

Empiric Regimens by Age

Adults <60 years 1:

• Preferred: Ceftriaxone 2g IV every 12 hours OR Cefotaxime 2g IV every 6 hours
• Alternative: Chloramphenicol 25 mg/kg IV every 6 hours
• Add vancomycin 15-20 mg/kg IV every 12 hours OR rifampicin 600 mg IV/PO every 12 hours if penicillin-resistant pneumococci suspected (e.g., recent arrival from high-resistance region) 1

Adults ≥60 years 1:

• Preferred: Ceftriaxone 2g IV every 12 hours OR Cefotaxime 2g IV every 6 hours PLUS Amoxicillin 2g IV every 4 hours (for Listeria coverage)
• Alternative: Chloramphenicol 25 mg/kg IV every 6 hours AND Co-trimoxazole 10-20 mg/kg (trimethoprim component) in 4 divided doses
• Add vancomycin or rifampicin if resistance suspected

Pediatric patients with meningitis 5:

• Initial dose: 100 mg/kg IV (not to exceed 4 grams)
• Maintenance: 100 mg/kg/day (not to exceed 4 grams daily), given once daily or divided every 12 hours
• Duration: 7-14 days typically

Neonates 5:

• Administer IV doses over 60 minutes (not 30 minutes) to reduce risk of bilirubin encephalopathy
• Ceftriaxone contraindicated in premature neonates and in neonates ≤28 days requiring calcium-containing IV solutions

Pathogen-Specific Treatment

Streptococcus pneumoniae 1

Penicillin-sensitive (MIC ≤0.06 mg/L):

• Benzylpenicillin 2.4g IV every 4 hours OR
• Ceftriaxone 2g IV every 12 hours OR
• Cefotaxime 2g IV every 6 hours
• Duration: 10 days if stable; up to 14 days if slow response

Penicillin-resistant but cephalosporin-sensitive:

• Continue ceftriaxone or cefotaxime
• Duration: 10-14 days

Penicillin AND cephalosporin resistant:

• Ceftriaxone 2g IV every 12 hours OR Cefotaxime 2g IV every 6 hours PLUS
• Vancomycin 15-20 mg/kg IV every 12 hours PLUS
• Rifampicin 600 mg IV/PO every 12 hours
• Duration: 14 days

Neisseria meningitidis 1

• Preferred: Ceftriaxone 2g IV every 12 hours OR Cefotaxime 2g IV every 6 hours
• Alternative: Benzylpenicillin 2.4g IV every 4 hours OR Chloramphenicol 25 mg/kg IV every 6 hours
• If not treated with ceftriaxone: Give single dose ciprofloxacin 500 mg PO for eradication 1
• Duration: 5 days if recovered

Listeria monocytogenes 1

• Preferred: Amoxicillin 2g IV every 4 hours
• Alternative: Co-trimoxazole 10-20 mg/kg (trimethoprim component) in 4 divided doses
• Duration: 21 days

Haemophilus influenzae 1

• Preferred: Cefotaxime 2g IV every 6 hours
• Alternative: Moxifloxacin 400 mg IV/PO once daily
• Duration: 10 days

Adjunctive Dexamethasone Therapy

Dexamethasone should be administered to children and adults with suspected bacterial meningitis before or at the time of antibiotic initiation 2. The evidence is strongest for:

• Adults with pneumococcal meningitis (reduces mortality and adverse outcomes) 6
• Children with H. influenzae type B meningitis 6

Dexamethasone must be given concomitant with or just prior to the first antimicrobial dose for maximal effect on subarachnoid space inflammation 6.

Supportive Care and Hemodynamic Management

Fluid Management 1

• Keep patients euvolemic to maintain normal hemodynamic parameters
• Do NOT restrict fluids in attempt to reduce cerebral edema
• Crystalloids are initial fluid of choice
• Consider albumin for persistent hypotensive shock despite corrective measures

Vasopressor Support 1

• Target mean arterial pressure (MAP) ≥65 mmHg (individualize based on age and cerebral edema presence)
• Norepinephrine is the vasopressor of choice (equivalent efficacy to dopamine with fewer adverse events)
• Consider hydrocortisone 200 mg once daily for persisting hypotensive shock

Seizure Management 1

• Treat suspected or proven seizures early
• Perform EEG monitoring for suspected status epilepticus (including non-convulsive status) in patients with fluctuating GCS off sedation

Intracranial Pressure Management 1

• Basic measures to control ICP and maintain cerebral perfusion pressure for suspected/proven raised ICP
• Routine ICP monitoring is NOT recommended

Complications and Follow-Up

Common Neurologic Complications 1

• Hearing loss (34% in children, 5-35% overall)
• Seizures (13%)
• Motor deficits (12%)
• Cognitive defects (9%)
• Hydrocephalus (7%)
• Visual loss (6%)

Mandatory Follow-Up 1

Hearing assessment:

• Perform during admission (otoacoustic emission screening in children; speech tone audiometry in adults)
• Repeat if initial test abnormal or clinical suspicion develops
• Early cochlear implant consideration prevents speech development delays in children

Neuropsychological evaluation:

• Indicated for patients with cognitive complaints post-discharge
• One-third of survivors have persisting complaints

Key Pitfalls to Avoid

1. Never delay antibiotics while awaiting CT or LP—start treatment within 1 hour regardless 1, 4
2. Do not falsely reassure based on low early warning scores—patients deteriorate rapidly 1
3. Do not assume viral meningitis based on lymphocytic CSF in partially treated cases 4
4. Do not discontinue antibiotics based on negative cultures alone if CSF parameters and clinical presentation suggest bacterial meningitis with prior antibiotic exposure 4
5. Do not use latex agglutination tests as they are surpassed by PCR 4
6. Do not forget Listeria coverage in patients ≥60 years 1
7. Do not administer ceftriaxone to neonates receiving calcium-containing IV solutions 5