A 45-year-old man presents with 4 days of high fever, severe headache, photophobia, and neck stiffness. CSF shows glucose 2.1 mmol/L (serum 6.8), protein 2.8 g/L, and WBC 2400 cells/μL (90% polymorphs). Gram stain shows gram-negative diplococci. The antibiotic of choice for treatment and the dose is:
- A IV Benzylpenicillin 2.4 g every 4 hours
- B IV Ceftriaxone 2 g every 12 hours ✓
- C IV Chloramphenicol 1 g every 6 hours
- D Oral ciprofloxacin 500 mg twice daily
Correct answer: B. IV Ceftriaxone 2 g every 12 hours
Explanation
Gram-negative diplococci in CSF represent Neisseria meningitidis (meningococcal meningitis). IV ceftriaxone 2 g every 12 hours (or 4 g daily) is the treatment of choice per WHO and UK guidelines, with excellent CSF penetration and bactericidal activity. Benzylpenicillin remains an alternative but has inferior CNS penetration and rising resistance. Chloramphenicol is reserved for penicillin/cephalosporin-allergic patients. Oral ciprofloxacin has no role in treatment (used for prophylaxis of contacts).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.