Lancefield grouping

Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls.

[1] The system, created by Rebecca Lancefield, was historically used to organize the various members of the family Streptococcaceae, which includes the genera Lactococcus and Streptococcus, but now is largely superfluous due to explosive growth in the number of streptococcal species identified since the 1970s.

The classification assigns a letter code to each serotype.

[3] 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.

Notably, enterococci and Streptococcus bovis (Lancefield group D) are not beta-hemolytic.