In bacterial meningitis, the exudate fills the subarachnoid space. Which cell type predominates in the CSF in acute purulent meningitis, and which organisms are most commonly responsible in neonates?

• A Lymphocytes; Haemophilus influenzae
• B Neutrophils (polymorphonuclear); Group B Streptococcus and E. coli ✓
• C Eosinophils; Cryptococcus neoformans
• D Monocytes; Listeria monocytogenes

Explanation

Acute bacterial meningitis causes a neutrophil-predominant CSF pleocytosis (PMN cells). In neonates (0–3 months), the commonest organisms are Group B Streptococcus (agalactiae), Escherichia coli (K1 capsule), and Listeria monocytogenes. Viral meningitis shows lymphocytic pleocytosis. Haemophilus influenzae type b was the leading cause in unvaccinated children but is rare since HiB vaccination.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.