| Appearance | Cells (mm3) | Cell type | Protein (g/L) | Glucose (%) | Probable etiology |
|---|---|---|---|---|---|
| Normal | <5 | Mononuclear cells | 0.15-0.45 | 60% of blood glucose (0.5 g/L) | Normal |
| Purulent meningitis | >10, often >1000 | Mostly polymorphonuclear (>50% PNN) | >0.4 | <40% | Bacterial (pyogenic organisms) |
| Clear fluid meningitis | >10, often >10-100 | Mixed or predominantly mononuclear (>50% lymphocytes) | >0.4 | Subnormal or normal | Viral (Enterovirus, VZV, HSV), TB, Listeria, early bacterial, fungal (cryptococcosis) |
Suspicion of purulent meningitis:
- Start antibiotics within 1 hour
- Don’t forget to sample blood cultures before starting antibiotics