Which drug is used for mass chemoprophylaxis for meningococcal meningitis?

Explanation

## Correct Answer: D. Ciprofloxacin Mass chemoprophylaxis for meningococcal meningitis requires an agent that achieves adequate cerebrospinal fluid (CSF) penetration, has good oral bioavailability for population-level administration, and covers *Neisseria meningitidis* effectively. **Ciprofloxacin** is the drug of choice for mass prophylaxis in India and globally because it is a fluoroquinolone with excellent CSF penetration (60–90% of serum levels), achieves bactericidal concentrations against meningococci, and is administered orally—making it ideal for rapid, large-scale prophylaxis during outbreaks. The standard regimen is 500 mg single dose or 250 mg BD for 2 days. While penicillin is the treatment drug for active meningococcal meningitis, it has poor oral bioavailability and requires parenteral administration, making it unsuitable for mass prophylaxis. Tetracycline and chloramphenicol, though historically used, have fallen out of favor due to resistance patterns and inferior pharmacokinetics for prophylaxis. Indian guidelines (RNTCP, IAP) and the National Centre for Disease Control (NCDC) recommend ciprofloxacin for chemoprophylaxis of close contacts and in outbreak settings. The key discriminator is that prophylaxis must be oral, rapid, and population-applicable—only ciprofloxacin meets all three criteria. ## Why the other options are wrong **A. Tetracycline** — Tetracycline has poor CSF penetration and is bacteriostatic rather than bactericidal against meningococci. Although it can be used for treatment in penicillin-allergic patients, it is not suitable for mass prophylaxis due to slow action and variable absorption. Resistance is also common in meningococcal strains in India. **B. Penicillin** — Penicillin is the gold-standard treatment for active meningococcal meningitis (parenteral benzylpenicillin or ceftriaxone), but it has negligible oral bioavailability and must be given intravenously or intramuscularly. This makes it impractical for mass chemoprophylaxis of contacts in outbreak settings where rapid, oral administration is essential. **C. Chloramphenicol** — Chloramphenicol achieves good CSF penetration but is bacteriostatic, not bactericidal, and carries risk of aplastic anemia and gray baby syndrome. It is reserved only for penicillin-allergic patients with meningococcal meningitis and is never used for prophylaxis due to toxicity concerns and inferior efficacy compared to fluoroquinolones. ## High-Yield Facts - **Ciprofloxacin 500 mg single dose** is the standard for meningococcal prophylaxis in India (NCDC/IAP guidelines). - **Fluoroquinolones** achieve 60–90% CSF penetration and are bactericidal against *Neisseria meningitidis*. - **Penicillin/cephalosporins** are treatment agents (not prophylaxis) and require parenteral administration. - **Prophylaxis is indicated** for household contacts, healthcare workers with respiratory exposure, and in outbreak settings within 24 hours of case identification. - **Rifampicin** is an alternative prophylactic agent (600 mg BD × 2 days) but ciprofloxacin is preferred due to single-dose convenience. ## Mnemonics **CIPRO for Prophylaxis (not Penicillin for Prophylaxis)** **C**iprofloxacin = **C**hemoprophylaxis (oral, rapid, population-scale). **P**enicillin = **P**arental (IV/IM only, for treatment). Use when distinguishing prophylaxis vs. treatment drugs. **FQ-CSF Rule** **F**luoro**Q**uinolones penetrate **CSF** well (60–90%) → suitable for prophylaxis. Beta-lactams penetrate CSF only when meninges are inflamed → unsuitable for prophylaxis of asymptomatic contacts. ## NBE Trap NBE may pair penicillin (the correct treatment drug for meningococcal meningitis) with the prophylaxis question to trap students who confuse treatment with prevention. The key is recognizing that prophylaxis requires oral, rapid, population-applicable dosing—a pharmacokinetic distinction, not a microbiological one. ## Clinical Pearl In Indian outbreak settings (schools, hostels, military barracks), ciprofloxacin 500 mg single dose is given to all close contacts within 24 hours of case identification. This single-dose convenience ensures compliance and rapid population coverage—critical in resource-limited settings where follow-up is challenging. Penicillin, though superior for treating active disease, cannot achieve this practical goal. _Reference: Jawetz, Melnick & Adelberg's Medical Microbiology Ch. 15 (Neisseria); KD Tripathi Essentials of Medical Pharmacology Ch. 47 (Fluoroquinolones); NCDC Guidelines on Meningococcal Disease Management (India)_