What is the best course of treatment for an 11-year-old male patient presenting with ataxia, nystagmus, delayed response to questions, history of intermittent fever, bradycardia, slight hypertension, and cerebrospinal fluid (CSF) analysis showing mild pleocytosis, elevated protein, and normal glucose, with magnetic resonance imaging (MRI) findings suggestive of meningitis?

Treatment of Suspected Bacterial Meningitis in an 11-Year-Old with Atypical CSF Findings

Immediate Empirical Antibiotic Therapy is Essential

This child requires immediate empirical antibiotic therapy with vancomycin plus ceftriaxone (or cefotaxime), initiated within one hour of presentation, despite the atypical CSF findings showing minimal pleocytosis. 1

The clinical presentation—ataxia, nystagmus, delayed responses, bradycardia, hypertension, and MRI findings of pachymeningeal and leptomeningeal enhancement with cranial nerve VII/VIII involvement—strongly suggests bacterial meningitis with complications, even though the CSF shows only 5 WBC/mm³. 1

Why the Low CSF White Cell Count Does Not Exclude Bacterial Meningitis

• Bacterial meningitis can present without pleocytosis, particularly early in the disease course. In a systematic review of 62 children with culture-proven bacterial meningitis and absent pleocytosis, 80% had fever for ≤24 hours before lumbar puncture. 2

• The CSF protein elevation (45 mg/dL) and normal glucose (69 mg/dL) with all lymphocytes on differential are concerning findings that do not exclude bacterial infection. 3

• The 10-day history of intermittent fever followed by current afebrile status with bradycardia suggests evolving intracranial complications rather than early disease. 4

• All CSF samples should be cultured even when cell count appears normal, especially with short or atypical symptom duration. 2

Recommended Empirical Antibiotic Regimen

Standard Therapy for Age 11 Years

• Vancomycin 60 mg/kg/day IV divided every 6 hours 5
• PLUS Ceftriaxone 100 mg/kg/day IV once daily (maximum 4 grams/day) 6, 5
• OR Cefotaxime 300 mg/kg/day IV divided every 6-8 hours 1, 5

This combination provides coverage against Streptococcus pneumoniae (including penicillin-resistant strains), Neisseria meningitidis, and Haemophilus influenzae. 1

Critical Timing Considerations

• Antibiotics must be administered within one hour of arrival, before any imaging studies if meningitis is suspected. 1

• Blood cultures should be obtained immediately before antibiotic administration. 1

• Do not delay treatment for lumbar puncture or imaging—the patient has already had CSF analysis. 1

Adjunctive Dexamethasone Therapy

Dexamethasone should be administered immediately, either shortly before or simultaneously with the first antibiotic dose. 1

• The standard dose is 0.15 mg/kg IV every 6 hours for 2-4 days. 1

• Dexamethasone has been shown to reduce mortality and morbidity in bacterial meningitis, particularly pneumococcal disease. 1, 7

Addressing the Atypical Clinical Features

Bradycardia and Hypertension (Cushing's Triad)

• The heart rate of 57-62 bpm with slight hypertension suggests elevated intracranial pressure (ICP). 4

• This represents a neurological emergency requiring immediate treatment and close monitoring. 1

• Symptomatic bradycardia in meningitis can result from intracranial hypertension and requires vigilant monitoring rather than immediate cardiac intervention. 4

Cranial Nerve Involvement

• Enhancement of bilateral VII and VIII nerve complexes on MRI indicates cranial neuritis, a recognized complication of bacterial meningitis. 1

• This finding supports the diagnosis of bacterial meningitis despite minimal CSF pleocytosis. 3

Ataxia and Nystagmus

• These cerebellar signs combined with cranial nerve VIII involvement suggest posterior fossa inflammation or increased ICP. 7

Essential Monitoring and Follow-Up

Repeat Lumbar Puncture Indications

• A second lumbar puncture should be performed at 48-72 hours if clinical response is inadequate or if pneumococcal meningitis with high MIC (>0.5 mg/L) is confirmed. 5, 2

• All children who had initial CSF without pleocytosis but underwent repeat LP showed abnormal CSF including pleocytosis on the second tap. 2

Duration of Therapy

• If Streptococcus pneumoniae with MIC <0.5 mg/L: continue ceftriaxone alone for 10 days total. 5

• If pneumococcal MIC ≥0.5 mg/L or inadequate response: continue vancomycin plus ceftriaxone for 14 days, consider adding rifampin. 5

• If Neisseria meningitidis or H. influenzae: ceftriaxone alone for 7 days. 5

• For meningitis in general: continue therapy for at least 2 days after signs and symptoms resolve, with usual duration 4-14 days. 6

Critical Pitfalls to Avoid

• Do not dismiss bacterial meningitis based solely on low CSF white cell count—this occurs in up to 20% of cases, particularly with short symptom duration or early presentation. 2

• Do not delay antibiotics for imaging or additional diagnostic procedures—mortality increases with treatment delays. 1

• Do not attribute bradycardia to primary cardiac pathology without considering elevated ICP as the cause. 4

• Do not use ceftriaxone monotherapy initially in an 11-year-old with suspected bacterial meningitis—vancomycin must be added for pneumococcal coverage given resistance patterns. 1

• Do not overlook the need for hearing evaluation after recovery, as cranial nerve VIII involvement predicts potential hearing loss. 1

Alternative Diagnostic Considerations

Tuberculous Meningitis

• The lymphocytic predominance, elevated protein, and cranial nerve involvement could suggest TB meningitis, especially with 10 days of fever. 8

• However, CSF glucose is typically markedly decreased in TB meningitis (not seen here), and the acute presentation with ataxia/nystagmus favors bacterial etiology. 3

• If cultures remain negative at 48-72 hours and clinical response is inadequate, consider TB meningitis and initiate anti-tuberculous therapy. 8

Viral Encephalitis

• The MRI findings and cranial nerve involvement could suggest viral encephalitis (HSV, VZV). 1

• However, the pachymeningeal enhancement and clinical severity warrant bacterial coverage. 1

• Consider adding aciclovir 500 mg/m² IV every 8 hours if viral encephalitis cannot be excluded and patient deteriorates despite antibiotics. 1