A 2-month-old infant presents with fever, poor feeding, and irritability. CSF analysis shows WBC 800/mm³ with neutrophilic predominance, protein 200 mg/dL, and glucose 20 mg/dL (blood glucose 85 mg/dL). What is the most likely causative organism?

• A Streptococcus pneumoniae
• B Neisseria meningitidis
• C Group B Streptococcus ✓
• D Haemophilus influenzae type b

Explanation

Group B Streptococcus (Streptococcus agalactiae) is the most common cause of bacterial meningitis in neonates and young infants under 3 months of age, along with Escherichia coli and Listeria monocytogenes. Streptococcus pneumoniae and Neisseria meningitidis are more common in older children. Haemophilus influenzae type b is now rare in countries with routine vaccination.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.