The epidemiology of beta-haemolytic non-group A streptococci isolated from the throats of children over a one-year period.

The incidence of beta-haemolytic non-Group A streptococci (BHNAS) in the throats of a paediatric population was examined over a 1-year period. There was minimal seasonal fluctuation of Lancefield groups including species and biotypes within Groups C and G streptococci. A trend of increasing incidence with age of Streptococcus anginosus ('Streptococcus milleri') (possessing Groups C and G Lancefield antigens) was evident. A clinical impression of streptococcal pharyngitis was more common in patients with large-colony Groups C or G streptococci isolated from their throats compared with those patients where other BHNAS were isolated. This study is requisite to the planning of case control studies which are required to test the association of BHNAS (especially Groups C and G subgroups) and pharyngitis.