Pediatrics Central Nervous system 3b289823 Most common organism causing meningitis in a 1 year old child A Streptococcus pneumoniae B H. influenza C Listeria D Neisseria meningitidIs High-Yield Explanation Streptococcus pneumonia is the most common organism causes meningitis even in the 1 year old child. Reference: GHAI Essential pediatrics, 8th edition