Which CSF profile confirms bacterial meningitis in an infant?

• A. Opening pressure 20 cm, clear, 30 mg/L protein, 75 mg/dL glucose, 15 cells/HPF
• B. Opening pressure 25 cm, fibrin webs visible, 100 mg/L protein, 45 mg/dL glucose, 100 cells/HPF
• C. Opening pressure 35 cm, turbid, 200 mg/L protein, 35 mg/dL glucose, 80,000 cells/HPF
• D. Opening pressure 40 cm, clear, 150 mg/L protein, 80 mg/dL glucose, 2,000 cells/HPF

Answer: (C)

Bacterial meningitis in infants typically shows a purulent, high-pressure CSF with marked neutrophilic pleocytosis, very elevated protein, and markedly low glucose. The profile described matches this pattern: opening pressure is elevated, the CSF appears turbid, protein is markedly increased, glucose is reduced, and there is an extremely high white cell count (neutrophil-predominant). This combination reflects the inflammatory response to bacterial invasion and the consumption of glucose by bacteria and inflammatory cells, which is why it most strongly confirms bacterial meningitis. In contrast, viral meningitis usually has clear CSF, with normal or mildly elevated protein, normal glucose, and a lymphocytic predominance with far fewer cells.