LINK Quick Facts Pneumococcal (S. Pneumoniae) Pneumococcal disease is a bacterial infection caused by S. pneumoniae (Streptococcus pneumonia). It is the most common cause of bacterial pneumonia and middle ear infection (otitis media) in the U.S., and is the third most frequent cause of bacterial meningitis. [i] Pneumococcal bacteria are often found in the … Continue reading