Harrison's Internal Medicine Chapter 128. Pneumococcal Infections Pneumococcal Infections: Introduction Streptococcus pneumoniae (the pneumococcus) was recognized as a major cause of pneumonia in the 1880s. Although the name Diplococcus pneumoniae was originally assigned to the pneumococcus, the organism was renamed Streptococcus pneumoniae because, like other streptococci, it grows in chains in liquid medium. Widespread vaccination has reduced the incidence of pneumococcal infection, but this organism remains the principal bacterial cause of otitis media, acute purulent rhinosinusitis, pneumonia, and meningitis. Microbiology Pneumococci are identified in the clinical laboratory as catalase-negative, gram-positive cocci that grow in pairs or chains and cause α-hemolysis on.
