Management of Suspected Bacterial Meningitis
Immediate Time-Critical Actions (Within 1 Hour)
Antibiotic therapy must be initiated within 1 hour of hospital arrival or clinical suspicion—any delay significantly increases mortality and neurological morbidity. 1, 2, 3
Step 1: Obtain Blood Cultures Immediately
- Draw blood cultures as soon as bacterial meningitis is suspected 2, 4
- Never delay antibiotics beyond 1 hour to obtain cultures 2
Step 2: Assess Need for Pre-Lumbar Puncture CT Scan
Perform urgent head CT only if any of the following high-risk features are present 2, 5:
- Age ≥60 years (adults) or immunocompromised state
- Known CNS disease (mass lesion, stroke, focal infection)
- New-onset seizure within past week
- Altered consciousness (GCS ≤12) or inability to follow commands
- Focal neurological deficits (gaze palsy, facial weakness, limb drift)
- Papilledema
If none of these criteria are present, proceed directly to lumbar puncture without CT imaging 2—the negative predictive value of this clinical decision rule is 97% 2
Step 3: Lumbar Puncture Timing
- No CT indicated: Perform LP immediately after blood cultures, within 1 hour of arrival 2
- CT indicated: Give antibiotics immediately after blood cultures, obtain CT, then defer LP unless scan shows no mass effect 2
- If LP cannot be completed within 1 hour: Start antibiotics immediately and perform LP as soon as possible, preferably within 4 hours (culture yield falls rapidly after this) 2
Empiric Antibiotic Regimens by Age
Neonates (0-3 months)
Ampicillin PLUS cefotaxime 1, 6, 2
- Ampicillin: 2g IV every 4 hours 2
- Cefotaxime: 2g IV every 6 hours 2
- Avoid ceftriaxone in neonates due to risk of fatal calcium-ceftriaxone precipitation 6
Infants and Children (3 months-18 years)
Cefotaxime (or ceftriaxone) PLUS vancomycin 1, 6, 2
- Ceftriaxone: 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 2
- Vancomycin: 15-20 mg/kg IV every 8-12 hours (target trough 15-20 µg/mL) 2
Adults <50 years
Ceftriaxone (or cefotaxime) PLUS vancomycin 2
- Ceftriaxone: 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours 2
- Vancomycin: 15-20 mg/kg IV every 8-12 hours (target trough 15-20 µg/mL) 2
Adults ≥50 years or Immunocompromised
Ceftriaxone (or cefotaxime) PLUS vancomycin PLUS ampicillin 2
- Add ampicillin 2g IV every 4 hours for Listeria monocytogenes coverage 2
- Risk factors for Listeria include age >50, diabetes, immunosuppressive drugs, cancer, and other immunocompromising conditions 2
Special Considerations for High Pneumococcal Resistance
- In regions with high pneumococcal resistance to penicillin and cephalosporins, vancomycin is essential 6, 2
- Consider adding rifampin 300 mg IV every 12 hours when dexamethasone is used, as steroids may reduce vancomycin CSF penetration 2
Adjunctive Dexamethasone Therapy
Dexamethasone should be administered immediately before or simultaneously with the first antibiotic dose to all patients with suspected bacterial meningitis 1, 6, 2, 4
Dosing by Age
- Adults: 10 mg IV every 6 hours for 4 days 2
- Children: 0.15 mg/kg IV every 6 hours for 2-4 days 6, 2
- Infants: 0.15 mg/kg IV every 6 hours for 4 days 1
Timing and Duration
- Give 10-20 minutes before or with first antibiotic dose 2
- Can still be started up to 4-12 hours after antibiotics without complete loss of benefit 2
- Continue for 4 days if pneumococcal meningitis is confirmed or probable 2
- Discontinue if non-bacterial etiology (viral, tuberculous) is identified 6
Evidence for Benefit
Dexamethasone reduces unfavorable outcomes (15% vs 25%; P=0.03) and mortality (7% vs 15%; P=0.04) in adults with bacterial meningitis 2. The effect is most pronounced in pneumococcal meningitis (unfavorable outcomes 26% vs 52%; deaths 14% vs 34%) 2.
Important Exception
Do not give dexamethasone to children with meningococcal septicemia (purpuric rash with shock) unless they develop inotrope-resistant shock 2
Hemodynamic Resuscitation in Septic Presentation
Fluid Resuscitation
- If shock is present (tachycardia, prolonged capillary refill >2 seconds, hypotension, altered consciousness), give 20 mL/kg isotonic crystalloid bolus rapidly 6, 2
- Reassess after each bolus; up to 60 mL/kg may be required in the first hour for severe meningococcal sepsis 6, 2
- Maintain mean arterial pressure ≥65 mm Hg to ensure adequate cerebral perfusion 2
Escalation to Intensive Care
- When >40-60 mL/kg fluid is needed or patient remains unstable, consult pediatric/adult intensive care immediately for inotropic and ventilatory support 6, 2
- Avoid aggressive fluid resuscitation unless septic shock is present 1
ICU Transfer Criteria
Transfer to intensive care immediately if any of the following are present 6, 2:
- Rapidly evolving purpuric rash (suggestive of meningococcal sepsis)
- Glasgow Coma Scale ≤12
- Cardiovascular instability requiring >40-60 mL/kg fluid resuscitation
- Respiratory compromise (hypoxia or increased work of breathing)
- Prolonged or recurrent seizures
- Signs of raised intracranial pressure
- National Early Warning Score ≥7 (or ≥5 with single parameter score of 3) 2
Expected Cerebrospinal Fluid Findings
| Parameter | Bacterial Meningitis Finding | Clinical Significance |
|---|---|---|
| Opening pressure | 200-500 mm H₂O | Indicates raised intracranial pressure [2] |
| WBC count | 1,000-5,000 cells/µL (range 100-110,000) | Reflects intense inflammatory response [2] |
| Differential | Neutrophils 80-95% (≈10% may be lymphocyte-predominant) | Supports bacterial etiology [2] |
| Glucose | <40 mg/dL in 50-60% of cases | Bacterial consumption of glucose [2] |
| CSF/serum glucose ratio | <0.4 in children >12 months; <0.6 in neonates | Distinguishes bacterial from viral meningitis [2] |
| Protein | Elevated (virtually all cases) | Blood-brain barrier disruption [2] |
Gram Stain Diagnostic Yield
- Overall sensitivity: 60-90% with 97% specificity 2
- Pathogen-specific positivity: S. pneumoniae 90%, H. influenzae 86%, N. meningitidis 75%, Gram-negative bacilli 50%, Listeria 33% 2
Common Pitfalls to Avoid
Timing Errors
- Never delay antibiotics for imaging or lumbar puncture—treatment must begin within 1 hour 2, 4, 5
- Appropriate clinical handling requires diagnosis ≤4 hours and antibiotic administration ≤2 hours 7
Antibiotic Selection Errors
- Never use vancomycin alone—it must be combined with a third-generation cephalosporin 2
- Never omit vancomycin from empiric regimen when resistant pneumococcal strains are a concern 2
- Never use ceftazidime as empiric therapy for community-acquired meningitis—reserve it for Pseudomonas coverage in nosocomial cases 2
- Never use penicillin alone for nosocomial meningitis, immunodeficient patients, or those recently visiting countries with high penicillin-nonsusceptible pneumococci prevalence 7
- Never use ampicillin as monotherapy for Gram-negative bacteria before susceptibility results are known 7
Dexamethasone Errors
- Never administer dexamethasone more than 12 hours after first antibiotic dose—timing is critical for benefit 2
- Never give dexamethasone to children with meningococcal septicemia unless inotrope-resistant shock develops 2
Lumbar Puncture Errors
- Never perform LP if CT reveals significant brain swelling, midline shift, or mass lesion 2
- In children, isolated brief seizures should not delay LP—seizures occur in up to 30% of pediatric bacterial meningitis cases and do not independently indicate raised intracranial pressure 2
Follow-Up and Long-Term Monitoring
Hearing Assessment
- Perform otoacoustic emission screening during admission 1
- Formal audiometry at 6-12 months post-treatment 1
- Rationale: 5-35% of survivors develop sensorineural hearing loss; 4% have severe bilateral hearing loss 1
- Hearing loss is the most common neurological sequela of pediatric bacterial meningitis 2
Neurological and Cognitive Assessment
- Assess for cognitive deficits, motor deficits, seizures, and behavioral problems at 3-6 months post-illness 6, 2
- Approximately one-third of survivors have persistent neurologic sequelae 1
- Psychiatric, psychosocial, and behavioral problems may develop after acute illness 2
Vaccination
- Provide pneumococcal vaccination to all survivors to reduce risk of recurrence 6
Chemoprophylaxis for Close Contacts
Indications
- Offer chemoprophylaxis within 24 hours of diagnosis to household members and close contacts of cases caused by N. meningitidis or H. influenzae type B 6, 2
- Close contacts include household members, dormitory residents, intimate partners, and those sharing sleeping quarters or kissing 6, 2