A 19-year-old female medical student is admitted with acute bacterial meningitis. CSF analysis shows pleocytosis with predominant polymorphonuclear leukocytes, elevated protein, and low glucose. Gram stain of CSF reveals gram-negative diplococci. What is the drug of choice for meningitis caused by Neisseria meningitidis?

## Drug of Choice for Meningococcal Meningitis **Key Point:** Ceftriaxone 2 g IV every 12 hours (or cefotaxime 2 g IV every 4–6 hours) is the first-line agent for bacterial meningitis caused by Neisseria meningitidis. ### Why Ceftriaxone is Superior 1. **CSF penetration**: Achieves bactericidal concentrations in cerebrospinal fluid (CSF penetration ~80% of serum levels) 2. **Spectrum**: Covers N. meningitidis, Streptococcus pneumoniae, and Listeria monocytogenes (when combined with ampicillin in high-risk groups) 3. **Resistance**: N. meningitidis remains universally susceptible to cephalosporins; penicillin resistance is rare but emerging in some regions 4. **Outcome**: Superior clinical cure rates and lower mortality compared to penicillin monotherapy ### Comparison of Agents for Meningitis | Agent | CSF Penetration | Spectrum | Resistance | Status | |-------|-----------------|----------|------------|--------| | **Ceftriaxone** | ~80% | N. mening., S. pneu., *Listeria* (with ampicillin) | Rare | **First-line DOC** | | **Penicillin G** | ~60% | N. mening., S. pneu. | Emerging in some regions | Acceptable if susceptible | | **Chloramphenicol** | ~90% | Broad spectrum | Increasing | Rarely used; toxicity | | **Vancomycin** | ~20% | Gram-positive only | N/A | Reserved for β-lactam allergy | **High-Yield:** Ceftriaxone is the empiric choice for meningitis in most age groups because it covers the three most common bacterial pathogens (N. meningitidis, S. pneumoniae, and—when combined with ampicillin—Listeria in neonates and elderly). **Mnemonic: "NSL" — Neisseria, Streptococcus, Listeria** — the three organisms covered by ceftriaxone (± ampicillin for Listeria). **Clinical Pearl:** N. meningitidis meningitis typically presents with acute onset of fever, headache, neck stiffness, and petechial or purpuric rash (in meningococcemia). Gram-negative diplococci on CSF Gram stain are pathognomonic. Empiric therapy should be started immediately; do not delay for culture results. **Warning:** Penicillin monotherapy is no longer recommended as first-line for meningitis in most regions due to emerging penicillin-resistant N. meningitidis (PRNM) and S. pneumoniae. Ceftriaxone or cefotaxime is mandatory. Vancomycin has poor CSF penetration (~20%) and should only be added if β-lactam allergy is confirmed or if highly resistant pneumococci are suspected. [cite:Harrison 21e Ch 137]