Which organism causes otitis media and meningitis in unvaccinated children?

• A. Haemophilus influenzae
• B. Streptococcus pneumoniae
• C. Staphylococcus aureus
• D. Pseudomonas aeruginosa

Answer: (A)

Haemophilus influenzae is the organism most classically associated with both otitis media and meningitis in young, unvaccinated children. Before the Hib vaccine, Haemophilus influenzae type b was a leading cause of bacterial meningitis in this age group, and it also commonly caused otitis media due to its ability to colonize and invade the upper respiratory tract and middle ear. The Hib vaccine targets type b and has dramatically reduced invasive Hib disease, including meningitis, in vaccinated populations. While other bacteria like Streptococcus pneumoniae can cause both conditions, the historical and textbook pairing in unvaccinated children is Haemophilus influenzae.