Streptococcus pneumoniae produces a second haemolysin that is distinct from pneumolysin.

Pneumococci are described as alpha-haemolytic but under certain circumstances they produce zones of beta-haemolysis on blood-containing medium. This observation was investigated using wild type strains and a genetically-modified strain unable to produce the haemolytic toxin, pneumolysin. beta-haemolysis was produced by all pneumococci tested. It was not inhibited by anti-pneumolysin antibody but could be inactivated by cholesterol. These data confirm that pneumococci elaborate a second haemolysin, distinct from pneumolysin.