A 6-month-old infant is brought with fever, irritability, bulging fontanelle, and reduced feeding for 24 hours. CSF analysis shows: glucose 18 mg/dL (blood glucose 90 mg/dL), protein 280 mg/dL, TLC 1800 cells/mm³ (90% neutrophils), and gram-negative coccobacilli on Gram stain. Which empirical antibiotic regimen is MOST APPROPRIATE for this age group?

• A IV cefotaxime or ceftriaxone plus ampicillin to cover Streptococcus pneumoniae, Listeria monocytogenes, and Haemophilus influenzae ✓
• B IV benzylpenicillin alone, as Neisseria meningitidis is the most likely organism
• C IV ceftriaxone alone, as third-generation cephalosporins provide adequate coverage for all neonatal and infant meningitis pathogens
• D IV vancomycin plus rifampicin for suspected penicillin-resistant pneumococcal meningitis

Explanation

In a 6-month-old infant with bacterial meningitis, the common causative organisms include Streptococcus pneumoniae, Haemophilus influenzae type b, and Neisseria meningitidis. Listeria monocytogenes is a consideration in this age group (though less common than neonates). The gram-negative coccobacilli on Gram stain suggest H. influenzae. Standard empirical therapy for infants 1–3 months is cefotaxime/ceftriaxone PLUS ampicillin (to cover Listeria, which is intrinsically resistant to cephalosporins). Ceftriaxone alone misses Listeria. Penicillin alone is inadequate. Vancomycin + rifampicin is used when penicillin-resistant pneumococcus is specifically suspected.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.