Which organism is the etiologic agent of epidemic cerebrospinal meningitis?

• A. Neisseria meningitidis
• B. Bordetella pertussis
• C. Haemophilus influenzae
• D. Streptococcus pneumoniae

Answer: (A)

Epidemic meningitis is most classically caused by Neisseria meningitidis. This organism spreads readily from person to person through respiratory droplets and thrives in crowded settings, such as dormitories or military barracks, leading to rapid outbreaks. It’s a Gram-negative diplococcus that can cause both meningitis and meningococcemia, the latter often with a petechial rash, highlighting its outbreak potential. The other organisms listed cause meningitis or related illnesses but are not the hallmark agents of epidemics in the same way. Bordetella pertussis causes whooping cough; Haemophilus influenzae type b was a common meningitis cause before vaccination but is not the epidemic agent it once was; Streptococcus pneumoniae is a major cause of bacterial meningitis overall but not specifically linked to epidemics.