pneumococcus /no̅o̅′mōkok″əs/ [Gk, pneumon + kokkos, berry] , a gram-positive diplococcal bacterium of the species Streptococcus pneumoniae, the most common cause of bacterial pneumonia. More than 85 subtypes of this organism are known. A vaccine protective against 35 serotypes has been developed and is recommended for those over 65 years of age, those with a chronic lung disease, or those with human immunodeficiency virus infection. See also lobar pneumonia, pneumonia, Streptococcus pneumoniae.
