[The frequency of Streptococcus anginosus in the pharyngeal exudate from children and its differentiation from other beta-hemolytic streptococci].

UNLABELLED: S. anginosus is a commensal of the oro-pharyngeal mucous membrane without any signification for the local pathology. Ignoring the existence of beta-haemolytic colonies of this species, the risk to report the presence of some beta-haemolytic streptococci that actually belong to the normal flora exists. The antigenic identifications of beta-haemolytic streptococci maintain the confusion either, S. anginosus being able to react with specific sera anti group G, C or A. In our study, two identification criteria out of those available demonstrated a high value: the small or very small colonies' size, especially in secondary cultures and the production of acetoin (Voges-Proskauer test). S. anginosus was isolated with a quite great frequency in pharyngeal exudate from children: 41 strains out of 90 strains of beta-haemolytic non-group A streptococci were S. anginosus. Antigenically they belonged, in numerical order to groups C, G, F or they were ungroupable. IN CONCLUSION: The microbiologist has to identify, but not to report the presence of S. anginosus in pharyngeal exudate, it being a normal component of the oro-pharyngeal flora. Doing so, a better evaluation of the clinical signification of the other beta haemolytic streptococci's non group A will be possible.