Lancefield grouping is a system of classification that classifies

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting ...

-negative

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is ...

cocci based on the carbohydrate composition of bacterial

antigen In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

s found on their

cell wall A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

s. 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. However, it has retained some clinical usefulness even after the taxonomic changes, and as of 2018, Lancefield designations are still often used to communicate medical microbiological test results. 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 ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus '' Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They ...

)'', 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 - ''

'' *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'.

References

{{Clinical microbiology techniques Bacteriology Microbiology techniques