A 19-year-old college student presents with high fever, headache, photophobia, and neck stiffness. CSF analysis: turbid, WBC 2,400/µL (95% neutrophils), protein 280 mg/dL, glucose 22 mg/dL (blood glucose 94 mg/dL). Gram stain shows gram-negative diplococci intracellularly. The most appropriate empiric antibiotic therapy is:

• A Intravenous ampicillin + gentamicin
• B Intravenous vancomycin + rifampicin
• C Oral ciprofloxacin — Neisseria meningitidis is susceptible
• D Intravenous ceftriaxone 2 g every 12 hours ✓

Explanation

Gram-negative intracellular diplococci in CSF with purulent meningitis in a young adult strongly indicate Neisseria meningitidis (meningococcal meningitis). Third-generation cephalosporins (ceftriaxone 2 g IV q12h or cefotaxime 2 g IV q4h) are the treatment of choice, providing excellent CSF penetration and activity against N. meningitidis. Ampicillin + gentamicin is used for neonatal meningitis (Listeria/GBS); vancomycin + rifampicin is for MRSA or penicillin-resistant pneumococcal meningitis; oral ciprofloxacin is used as post-exposure prophylaxis for contacts, not treatment.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.