How to Tell Bacterial vs Viral Meningitis

November 4, 2020

Written by Clay Smith

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The meningitis score for emergencies appears to be very accurate in predicting bacterial vs viral meningitis, but it needs further prospective external validation before we put it into practice.

Why does this matter?
Previous scores have attempted to sort out bacterial vs viral meningitis. But the diagnostic accuracy of such scores must be very high to avoid missing bacterial meningitis. How does this score fare?

MSE – not just mental status exam anymore…
This was a retrospectively derived (n=819) and prospectively validated (n=190) score to distinguish bacterial from viral meningitis in children 29 days to 14 years of age in 25 Spanish EDs. In the derivation cohort, they found the following predictors were best and gave them a weighted score dubbed the Meningitis Score for Emergencies (MSE).

• Serum procalcitonin >1.20 ng/mL – 3 points

• Serum CRP >40 mg/L – 1 point

• CSF ANC >1000/μL – 1 point

• CSF protein >80 mg/dL – 2 points

When the MSE was applied to the entire cohort, 1,009 patients, the diagnostic performance (with 95%CI) of a score ≥1 was:

• Sensitivity 100% (95.0–100)

• Specificity 83.2 (80.6–85.5)

• PPV 37.4 (31.4–43.8)

• NPV 100 (99.4–100)

No cases of bacterial meningitis would have been missed with the MSE. This needs prospective external validation before we rely on this in practice. But this is a promising scoring system and may be an improvement on the Bacterial Meningitis Score.

Source
Clinical Prediction Rule for Distinguishing Bacterial From Aseptic Meningitis. Pediatrics. 2020 Sep;146(3):e20201126. doi: 10.1542/peds.2020-1126. Epub 2020 Aug 25.

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