What is the management approach for a patient with neutrophilic pleocytosis on lumbar puncture (LP) suggestive of acute bacterial meningitis and absent oligoclonal bands?

Management of Neutrophilic Pleocytosis with Absent Oligoclonal Bands

Absent oligoclonal bands in the setting of neutrophilic pleocytosis on lumbar puncture does NOT exclude bacterial meningitis and should not alter your immediate management—treat empirically for bacterial meningitis based on the CSF profile and clinical presentation. 1, 2

Key Diagnostic Context

Oligoclonal bands are not part of the standard diagnostic workup for acute bacterial meningitis and their absence has no bearing on the diagnosis or management of suspected bacterial infection. 1

• Oligoclonal IgG bands typically indicate intrathecal antibody production seen in chronic inflammatory CNS conditions (multiple sclerosis, neurosarcoidosis) or occasionally in para-infectious immune responses that develop after the acute bacterial phase 3
• In acute bacterial meningitis, the initial immune response is characterized by neutrophilic pleocytosis without oligoclonal band formation 1
• One case report documented oligoclonal bands appearing only after successful bacterial meningitis treatment, during a subsequent para-infectious immune phase with lymphocytic predominance 3

Immediate Management Algorithm

1. Confirm Bacterial Meningitis Profile

Neutrophilic pleocytosis strongly suggests bacterial meningitis when accompanied by: 1

• CSF glucose <40 mg/dL or CSF:plasma glucose ratio <0.36 (93% sensitivity/specificity for bacterial meningitis) 1
• CSF protein >0.6 g/L (bacterial meningitis unlikely if <0.6 g/L) 1
• Total CSF WBC typically >1000 cells/mm³ (though 10% of bacterial meningitis cases have <100 cells/mm³) 1
• Elevated opening pressure (>20 cm CSF) 1

2. Initiate Empiric Antibiotics Immediately

Do not delay antibiotics beyond 1 hour of hospital arrival, regardless of oligoclonal band status or any other pending test results: 2, 4, 5

For adults <60 years without immunocompromise:

• Ceftriaxone 2g IV every 12 hours PLUS Vancomycin 15-20 mg/kg IV every 8-12 hours 5, 6

For adults ≥60 years or immunocompromised:

• Add Ampicillin 2g IV every 4 hours to cover Listeria monocytogenes 5, 7

For children ≥1 month:

• Vancomycin plus ceftriaxone or cefotaxime pending culture results 2

3. Obtain Critical Diagnostic Studies

Before or simultaneously with antibiotic administration: 4, 5

• Blood cultures (positive in 71% of cases even when CSF culture negative, especially after antibiotics) 2, 8
• Pneumococcal and meningococcal PCR from blood (EDTA sample)—remains positive even after antibiotics started 4
• Concurrent plasma glucose for CSF:plasma ratio calculation 1, 4
• Procalcitonin (helps differentiate bacterial from viral with high sensitivity/specificity) 4

From CSF: 4

• Gram stain (50-99% sensitivity, though drops ~20% if antibiotics given pre-LP) 1, 2
• Culture (gold standard but may be negative within 2-4 hours of antibiotics) 2
• Multiplex PCR (87-100% sensitivity, remains positive after antibiotics) 2
• CSF lactate if obtained before antibiotics (93% sensitivity/specificity, but drops to <50% after antibiotics) 1, 2

Critical Pitfalls to Avoid

Never assume viral meningitis based on atypical features:

• Bacterial meningitis can present with minimal or absent pleocytosis (10% have <100 cells/mm³), especially early in illness 1, 8, 9
• Lymphocytic predominance can occur in bacterial meningitis (Listeria, partially treated cases) 1, 2
• Normal CSF at initial LP does not exclude bacterial meningitis—mortality in such cases is 31% for bacterial organisms 8, 9

Do not discontinue antibiotics prematurely:

• If CSF cultures are negative but clinical presentation and CSF parameters (elevated WBC, low glucose, high protein) suggest bacterial meningitis, continue antibiotics for full course (10-14 days for pneumococcus, 5-7 days for meningococcus) 2, 5
• Negative cultures may reflect pre-LP antibiotic administration rather than absence of infection 2

Consider repeat lumbar puncture if:

• Initial CSF was normal but clinical suspicion remains high 9
• Patient received antibiotics before first LP and diagnosis remains uncertain 2

Duration and Monitoring

• Minimum treatment duration: 48-72 hours beyond clinical improvement or bacterial eradication 7
• Streptococcus pneumoniae: 10-14 days 5
• Neisseria meningitidis: 5-7 days 5
• Perform hearing assessment during admission and repeat if abnormal 5