A 28-year-old man from Delhi presents with acute onset fever, headache, and neck stiffness. CSF analysis shows elevated protein (180 mg/dL), low glucose (20 mg/dL), and pleocytosis with predominant PMNs. Gram stain reveals gram-positive diplococci. All of the following are true regarding bacterial meningitis caused by Neisseria meningitidis EXCEPT:

Explanation

## Neisseria meningitidis Meningitis: Key Clinical Features ### Correct Answer Analysis **Dexamethasone timing:** The statement is INCORRECT because dexamethasone should be administered **BEFORE or WITH the first antibiotic dose**, not after lumbar puncture. Current guidelines recommend giving dexamethasone immediately upon clinical suspicion of bacterial meningitis, ideally before or concurrent with the first antibiotic dose. Delaying dexamethasone until after LP reduces its efficacy in reducing inflammation and improving outcomes. ### Why the Other Options Are Correct | Feature | Details | |---------|----------| | **Petechial/purpuric rash** | Pathognomonic for meningococcemia; occurs in 50–80% of cases; may appear before meningeal signs; indicates disseminated disease | | **Ceftriaxone** | First-line agent (2 g IV Q4H); excellent CSF penetration (70–90% of serum levels); bactericidal against N. meningitidis | | **Rifampicin prophylaxis** | Standard for household and close contacts; reduces nasopharyngeal carriage; dose 600 mg BD × 2 days (or 4 doses Q6H) | ### High-Yield Clinical Pearls **Key Point:** Dexamethasone (10 mg IV Q6H × 4 days) reduces mortality and neurological sequelae in bacterial meningitis when given early—ideally before antibiotics in suspected cases. **Clinical Pearl:** Do NOT delay antibiotics while awaiting LP if meningitis is clinically suspected. Start empiric antibiotics immediately in the emergency department, then perform LP. **Mnemonic — N. meningitidis Features: "PETRI"** - **P**etechial rash (pathognomonic) - **E**pidemic potential (close contacts at risk) - **T**ransient bacteremia (can seed blood cultures) - **R**ifampicin prophylaxis (contacts) - **I**ntensive care often needed (fulminant disease) ### Antibiotic Regimen for Meningococcal Meningitis 1. **Ceftriaxone** 2 g IV Q4H (or cefotaxime 2 g IV Q4–6H) 2. **Vancomycin** 15–20 mg/kg IV Q8–12H (for penicillin-resistant strains, though rare in N. meningitidis) 3. **Dexamethasone** 10 mg IV Q6H × 4 days (start before or with first antibiotic) 4. **Prophylaxis for contacts:** Rifampicin 600 mg PO BD × 2 days (or ciprofloxacin 500 mg PO single dose) [cite:Harrison 21e Ch 297] [cite:Robbins 10e Ch 7]