A 32-year-old woman from Mumbai presents with a 3-day history of fever, headache, and myalgias. On examination, she has a maculopapular rash on the trunk and extremities, but no neck stiffness or Kernig sign. Her vital signs are stable. CSF analysis shows: WBC 120/μL (80% lymphocytes), protein 65 mg/dL, glucose 48 mg/dL (serum glucose 95 mg/dL), Gram stain and bacterial culture negative. What is the most appropriate next step in management?

Explanation

## Diagnosis and Management of Viral Meningitis with Low CSF Glucose ### CSF Profile Analysis | Parameter | Finding | Interpretation | |-----------|---------|----------------| | WBC count | 120/μL | Mild pleocytosis (viral typically 10–1000/μL) | | Lymphocytic predominance | 80% | Suggests viral or TB meningitis | | Protein | 65 mg/dL | Mildly elevated (viral: 40–100 mg/dL) | | Glucose (CSF:serum ratio) | 48:95 (0.50) | **Low** — typically seen in bacterial, TB, or fungal meningitis | | Gram stain & culture | Negative | Rules out bacterial meningitis | **Key Point:** Low CSF glucose (ratio <0.40) with lymphocytic pleocytosis and negative bacterial cultures is most consistent with **viral meningitis**, particularly **enteroviral meningitis**. Enteroviruses can occasionally present with CSF glucose ratios as low as 0.30–0.50, which may mimic bacterial meningitis. ### Why This Is Viral, Not Bacterial Meningitis **High-Yield:** The combination of: 1. **Negative Gram stain and culture** — excludes bacterial pathogens 2. **Lymphocytic predominance** — bacterial meningitis typically shows PMN predominance early (>80% neutrophils) 3. **Stable vital signs and no neck stiffness** — suggests milder course typical of viral meningitis 4. **Maculopapular rash** — consistent with enteroviral exanthem **Clinical Pearl:** Enteroviral meningitis is the most common cause of aseptic meningitis in tropical regions like India. Enteroviruses (Coxsackievirus, Echovirus) can present with CSF findings that overlap with bacterial meningitis, including low glucose. However, negative cultures and lymphocytic predominance are reassuring. ### Management Strategy **Mnemonic:** **SAVE** = **S**upport (fluids, analgesics), **A**void unnecessary antibiotics, **V**iral PCR (enterovirus, HSV), **E**nsure supportive care. 1. **Obtain viral diagnostics:** Enterovirus PCR and viral culture from CSF are the gold standard for diagnosis. 2. **Supportive care:** Analgesics (paracetamol, NSAIDs), IV fluids, bed rest. 3. **No antibiotics:** Since bacterial meningitis is excluded by negative cultures and lymphocytic profile, continuing antibiotics is unnecessary. 4. **No acyclovir:** Unless HSV meningitis is suspected (typically with higher protein and CSF pleocytosis >500/μL, or if patient had recurrent meningitis). This patient's presentation is more consistent with enteroviral meningitis. **Warning:** Do NOT continue empirical antibiotics in a patient with negative CSF cultures and lymphocytic pleocytosis — this increases antibiotic resistance and exposes the patient to unnecessary toxicity. [cite:Harrison 21e Ch 384; Robbins 10e Ch 28]