Selective medium for isolation of Arcanobacterium haemolyticum and Streptococcus pyogenes.

Sheep blood agar using tryptic soy agar base and containing 3.5% sodium chloride was found to facilitate isolation of Arcanobacterium haemolyticum and improve isolation of Voges-Proskauer negative group A (Streptococcus pyogenes) and group C and G beta-haemolytic streptococci. Commensal oropharyngeal flora such as viridans streptococci, Neisseria species, non-haemolytic streptococci and beta-haemolytic streptococci not belonging to groups A, B, C or G were significantly inhibited.