A 10-day-old term infant presents with poor feeding, temperature instability, apnea, and bulging fontanelle. CSF shows 300 cells per microliter with neutrophil predominance and low glucose. The most common causative organism of neonatal bacterial meningitis is:

• A Streptococcus agalactiae ✓
• B Haemophilus influenzae type b
• C Neisseria meningitidis
• D Listeria monocytogenes

Explanation

Group B Streptococcus (Streptococcus agalactiae) acquired from maternal vaginal colonization is the leading cause of neonatal bacterial meningitis, followed by Escherichia coli and Listeria monocytogenes, which together form the classic neonatal triad guiding empiric ampicillin plus gentamicin or cefotaxime. Haemophilus influenzae type b peaks between 2 months and 5 years and has become rare after vaccination, while Neisseria meningitidis affects older children and adolescents.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.