Lancefield grouping is a method of grouping
catalase-negative,
coagulase-negative bacteria based on the carbohydrate composition of bacterial
antigens found on their cell walls. 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 has since been largely abandoned due to explosive growth in the number of streptococcal species identified since the 1970s. Enterococcus, formerly known as Group D Streptococcus, was believed to be a member of the genus Streptococcus until 1984, after the Lancefield criteria were devised, and so were included in the original Lancefield grouping. Many - but not all - species of streptococcus are beta-hemolytic. Notably, Enterococcus and Streptococcus bovis (Lancefield Group D) are not beta-hemolytic. Though there are many groups of streptococcus, only five are known to commonly cause disease in immune-competent human beings: Group A, Group B, both members of Group D, and two groups that lack the Lancefield carbohydrate antigen:
streptococcus pneumoniae and
Viridans streptococci.