Lancefield grouping

The classification assigns a letter code to each serotype. There are 20 described serotypes assigned the letters A to V (excluding E, I and J). Bacteria of the genus Enterococcus, formerly known as group D streptococci, were classified as members of the genus Streptococcus until 1984 and are included in the original Lancefield grouping. Many—but not all—species of streptococcus are beta-hemolytic. Notably, enterococci and Streptococcus bovis (Lancefield group D) are not beta-hemolytic. Though there are many groups of streptococci, the principal organisms that are known to cause human disease belong to group A (Streptococcus pyogenes), group B (Streptococcus agalactiae), group C/G (Streptococcus dysgalactiae) both members of group D (Streptococcus gallolyticus and Streptococcus infantarius, both members of the Streptococcus bovis group), and two alpha-haemolytic groups that lack the Lancefield carbohydrate antigen: Streptococcus pneumoniae and viridans streptococci.

Classification

• Group A - Streptococcus pyogenes
• Group B - Streptococcus agalactiae
• Group C - Streptococcus equisimilis, Streptococcus equi, Streptococcus zooepidemicus, Streptococcus dysgalactiae
• Group D - Enterococcus faecalis, Enterococcus faecium, Enterococcus durans and Streptococcus bovis
• Group F, G & L - Streptococcus anginosus
• Group G - Streptococcus dysgalactiae
• Group H - Streptococcus sanguis
• Group K - Streptococcus salivarius
• Group L - Streptococcus dysgalactiae
• Group M & O - Streptococcus mitis
• Group N - Lactococcus lactis
• Group R & S - Streptococcus suis

Other Streptococcus species are classified as 'non-Lancefield streptococci'.