A 28-year-old man from Delhi presents to the emergency department with a 2-day history of high fever (39.8°C), severe frontal headache, neck stiffness, and photophobia. On examination, he is alert but irritable, with a positive Kernig sign and Brudzinski sign. Blood pressure is 110/70 mmHg, heart rate 102/min. A non-blanching petechial rash is noted over the trunk and lower limbs. CSF analysis shows: WBC 450/μL (90% neutrophils), protein 180 mg/dL, glucose 25 mg/dL (serum glucose 110 mg/dL), Gram stain shows Gram-negative diplococci. Blood culture is pending. What is the most appropriate immediate management?

## Clinical Diagnosis This patient has **bacterial meningitis** with clinical and laboratory features consistent with **Neisseria meningitidis** (meningococcal meningitis): - Classic triad: fever, headache, neck stiffness - Positive meningeal signs (Kernig, Brudzinski) - **Non-blanching petechial rash** — pathognomonic for meningococcemia - CSF pleocytosis with neutrophil predominance, elevated protein, low glucose (CSF:serum glucose ratio ~0.23, <0.4 is bacterial) - Gram-negative diplococci on Gram stain ## Antibiotic Selection for Bacterial Meningitis **Key Point:** Empiric therapy for bacterial meningitis in adults must cover *Streptococcus pneumoniae*, *Neisseria meningitidis*, and *Listeria monocytogenes* (if age >50 or immunocompromised). | Agent | Indication | CNS Penetration | Notes | |-------|-----------|-----------------|-------| | **Ceftriaxone** | First-line for meningitis | Excellent (15–20% of serum) | 2 g IV 6-hourly (meningitis dosing) | | **Vancomycin** | Pneumococcal resistance coverage | Moderate (10–20%) | Always added empirically until susceptibilities known | | **Acyclovir** | HSV/VZV coverage | Moderate | Added empirically in meningitis to cover viral pathogens until excluded | | **Penicillin G** | Meningococcal monotherapy | Excellent | Adequate only if susceptibility confirmed; not empiric first-line | | **Gentamicin** | Gram-negative coverage | Poor CNS penetration | Inadequate for meningitis; used only for Gram-negative rods (e.g., Enterobacteriaceae) | | **Chloramphenicol** | Historical agent | Good CNS penetration | Rarely used now; reserved for penicillin allergy | **High-Yield:** The **empiric regimen for bacterial meningitis in adults** is: - **Ceftriaxone 2 g IV 6-hourly** (or cefotaxime 2 g IV 4-hourly) - **PLUS vancomycin 15–20 mg/kg IV 8-hourly** (for pneumococcal resistance) - **PLUS acyclovir 10 mg/kg IV 8-hourly** (to cover HSV/VZV until ruled out) This triple therapy is given **regardless of Gram stain result** until culture and susceptibilities are available. ## Why Ceftriaxone + Vancomycin + Acyclovir? 1. **Ceftriaxone** — excellent CSF penetration, covers both *N. meningitidis* and *S. pneumoniae* 2. **Vancomycin** — added because some pneumococci are penicillin-resistant; achieves adequate CSF levels only with high-dose IV therapy 3. **Acyclovir** — empirically covers HSV meningitis, which can coexist or mimic bacterial disease; safe to add **Clinical Pearl:** Even though Gram stain shows Gram-negative diplococci (almost certainly *N. meningitidis*), **do not de-escalate to penicillin G monotherapy** until culture confirms susceptibility and the clinical picture is unambiguous. Empiric broad coverage is standard of care. ## Adjunctive Therapy **Key Point:** Dexamethasone 10 mg IV 6-hourly for 4 days should be given **before or with the first antibiotic dose** to reduce inflammation and improve outcomes (especially in pneumococcal meningitis). ## Infection Control - **Respiratory isolation** for 24 hours after starting antibiotics - **Chemoprophylaxis** for close contacts: rifampicin 600 mg 12-hourly × 2 days, or ciprofloxacin 500 mg single dose, or ceftriaxone 250 mg IM single dose