What is the appropriate management for a patient suspected of having meningitis?

Management of Suspected Bacterial Meningitis

All patients with suspected bacterial meningitis must receive empirical antibiotics within 1 hour of hospital presentation—ceftriaxone 2g IV every 12 hours (or cefotaxime 2g IV every 6 hours) as the cornerstone, with ampicillin 2g IV every 4 hours added for patients ≥60 years or immunocompromised, and vancomycin 15-20 mg/kg IV every 12 hours added only if recent travel to areas with penicillin-resistant pneumococci. 1, 2, 3

Critical Timing Principle

• Antibiotic administration must never be delayed beyond 1 hour of presentation for any reason—not for lumbar puncture, not for CT imaging, not for any diagnostic procedure. 1, 2, 3
• Blood cultures should be obtained immediately before antibiotics when possible, but this must not delay treatment beyond the 60-minute window. 1, 2
• Delays in antibiotic treatment are directly associated with increased mortality and worse neurological outcomes. 3, 4

Empirical Antibiotic Regimens by Patient Population

Adults <60 Years (Immunocompetent)

• Ceftriaxone 2g IV every 12 hours OR cefotaxime 2g IV every 6 hours provides coverage for Streptococcus pneumoniae (72% of cases) and Neisseria meningitidis (11% of cases), the two most common pathogens in this age group. 5, 1, 4
• Third-generation cephalosporins are the backbone because they have excellent bactericidal activity against pneumococci and meningococci with superior penetration into inflamed meninges. 5, 6

Adults ≥60 Years or Immunocompromised

• Add ampicillin 2g IV every 4 hours to the cephalosporin regimen to cover Listeria monocytogenes, which becomes increasingly prevalent in older adults and immunocompromised patients. 5, 1, 7
• Risk factors for Listeria include age ≥60 years, diabetes mellitus, immunosuppressive drugs, cancer, alcohol misuse, and other immunocompromising conditions. 5, 3, 4
• This is the most commonly missed coverage error—never omit ampicillin in these populations. 1, 3

Special Circumstances: Penicillin-Resistant Pneumococci

• Add vancomycin 15-20 mg/kg IV every 12 hours OR rifampicin 600mg IV/PO every 12 hours if the patient has traveled within the past 6 months to areas with high rates of penicillin-resistant S. pneumoniae. 5, 2, 3
• Check local resistance patterns or consult infectious disease expertise if unsure about geographic risk. 5

Severe Penicillin/Cephalosporin Allergy

• If there is a clear history of anaphylaxis to beta-lactams, use chloramphenicol 25 mg/kg IV every 6 hours as the alternative. 5, 3

Adjunctive Dexamethasone Therapy

• Give dexamethasone 10mg IV every 6 hours starting with or shortly before the first antibiotic dose, and continue for 4 days if pneumococcal meningitis is confirmed or highly suspected. 1, 8, 4
• Dexamethasone reduces mortality and neurologic sequelae in pneumococcal meningitis but should be stopped if Listeria monocytogenes is confirmed. 8, 4

Diagnostic Approach

When to Perform CT Before Lumbar Puncture

• Obtain CT imaging before lumbar puncture if the patient has: 5, 3, 4
  • Altered mental status (Glasgow Coma Scale <10)
  • Focal neurological deficits
  • New-onset seizures
  • Papilledema
  • Severely immunocompromised state
  • History of CNS disease or mass lesion
• However, start antibiotics immediately before imaging—do not wait for CT results to initiate treatment. 1, 3, 9

CSF Analysis Criteria Suggestive of Bacterial Meningitis

• Suspect bacterial meningitis if any of the following are present: 4
  • CSF leukocytes >2000/μL
  • CSF granulocytes >1180/μL
  • CSF protein >2.2 g/L
  • CSF glucose <34.23 mg/dL
  • Positive Gram stain (sensitivity 50-90%)
• Blood cultures and CSF should be sent for culture and PCR testing, which has sensitivity of 87-100% and specificity of 98-100%, especially useful if antibiotics were given before lumbar puncture. 5

Pathogen-Specific De-escalation After Culture Results

Streptococcus pneumoniae

• Continue ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours for 10-14 days total. 5, 1, 3, 10
• If penicillin-sensitive (MIC ≤0.06 mg/L), may switch to benzylpenicillin 2.4g IV every 4 hours. 5, 3
• If both penicillin and cephalosporin resistant, continue ceftriaxone/cefotaxime plus vancomycin 15-20 mg/kg IV every 12 hours plus rifampicin 600mg IV/PO every 12 hours for 14 days. 5

Neisseria meningitidis

• Continue ceftriaxone 2g IV every 12 hours or cefotaxime 2g IV every 6 hours for 5-7 days total. 5, 1, 3
• If not treated with ceftriaxone, give a single dose of 500mg ciprofloxacin orally to eliminate nasopharyngeal carriage. 5, 3

Listeria monocytogenes

• Continue ampicillin 2g IV every 4 hours for 21 days total. 3, 7
• Stop dexamethasone if Listeria is confirmed. 4

Common Pitfalls to Avoid

• Never delay antibiotics for imaging or lumbar puncture—the 1-hour window is absolute and non-negotiable. 1, 3, 9
• Never omit ampicillin in patients ≥60 years or immunocompromised—inadequate Listeria coverage is a frequent and preventable error. 1, 3
• Never use inadequate dosing—high doses are essential for adequate CSF penetration (ceftriaxone 2g every 12 hours, not lower doses). 3
• Never stop antibiotics prematurely based on clinical improvement alone—complete the full pathogen-specific duration as microbiological cure does not equal clinical improvement. 5, 3

Supportive Care and Monitoring

• Patients with decreased level of consciousness, rapidly evolving petechial rash, cardiovascular instability, or uncontrolled seizures require immediate critical care assessment and potential ICU admission. 1
• Audiology testing should be performed post-treatment to assess for hearing loss, which occurs in up to 24% of survivors. 10, 4