This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Most common cause of acute pyogenic meningitis in adolescents and young adults: September 2003 
Select and explain. 
A. H. influenzae, B. N. meningitidis, C. Staph. aureus, D. Group B streptococci
B: N. meningitidis
Answer: B: N. meningitidis 
Explanation: Ans. B i.e. N. meningitidis Acute pyogenic (bacterial) meningitidis The micro-organism that cause acute pyogenic meningitis vary with the age of the affected individual. In neonates, they include Escherichia coli and the group B streptococci At the other extreme of life, Streptococcus pneumoniae and Listeria monocytogenes are more common. Among adolescents and in young adults, Neisseria meningitides is the most common pathogen, with clusters of cases causing frequent public health concerns.