Pneumococcus is probably the most common and most important pathogen amongst the streptococci. It is a normal commensal of the upper respiratory tract.
Pneumococcus is a Gram-positive lanceolate diplococcus with an antigenic carbohydrate capsule which conveys virulence.
Pneumococcus shows alpha haemolytic activity but is distinguished from viridans streptococci by draughtsman / mucoid colonies, optochrin sensitivity and bile solubility.
Pneumococcus is not Lancefield groupable (1)
Last reviewed 01/2018