Comparison of beta-hemolytic streptococci of group B (S.agalactiae) and group C. Beta-hemolysis in Streptococcus agalactiae (grou B beta-hemolytic streptococci) is usually less distinct (zones are not so clear) and may be absent in some strains, particularly under aerobic conditions.
Columbia agar with 5% defibrinated sheep blood. Cultivation 24 hours in an aerobic atmosphere enriched with 5% carbon dioxide.