Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain 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 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 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. Enterococcus, formerly known as Group D Streptococcus, were classified as members of the genus Streptococcus until 1984 and were 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 streptococcus, only five are known to commonly cause disease in immune-competent human beings: Group A, Group B, both members of Group D (''Streptococcus gallolyticus'' and ''Streptococcus infantarius'', both members of the ''Streptococcus bovis'' group), and two 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 equisimilis'' is a species of ''Streptococcus'', initially described by Frost in 1936. As a result of several DNA hybridization studies in 1983, the species was merged into ''Streptococcus dysgalactiae''. Subsequently, ''S.dysgal ...

'', ''

Streptococcus equi ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...

'', ''

Streptococcus zooepidemicus ''Streptococcus zooepidemicus'' is a Lancefield group C streptococcus that was first isolated in 1934 by P. R. Edwards, and named Animal pyogens A. It is a mucosal commensal and opportunistic pathogen that infects several animals and humans, but m ...

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Streptococcus dysgalactiae ''Streptococcus dysgalactiae'' is a gram positive, beta-haemolytic, coccal bacterium belonging to the family ''Streptococcaceae''. It is capable of infecting both humans and animals, but is most frequently encountered as a commensal of the alim ...

'' *Group D - '' Enterococcus faecalis'', ''

Enterococcus faecium ''Enterococcus faecium'' is a Gram-positive, gamma-hemolytic or non- hemolytic bacterium in the genus '' Enterococcus''. It can be commensal (innocuous, coexisting organism) in the gastrointestinal tract of humans and animals, but it may als ...

'', '' Enterococcus durans'' and '' Streptococcus bovis'' *Group F, G & L - ''

Streptococcus anginosus ''Streptococcus anginosus'' is a species of ''Streptococcus ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria) ...

'' *Group H - ''

Streptococcus sanguis ''Streptococcus sanguinis'', formerly known as ''Streptococcus sanguis'', is a Gram-positive facultative anaerobic coccus species of bacteria and a member of the Viridans Streptococcus group. ''S. sanguinis'' is a normal inhabitant of the healt ...

'' *Group K - ''

Streptococcus salivarius ''Streptococcus salivarius'' is a species of spherical, gram-positive, facultative anaerobic lactic acid bacteria that is both catalase and oxidase negative. ''S. salivarius'' colonizes (usually in chains) the oral cavity and upper respiratory ...

'' *Group L - ''

'' *Group M & O - '' Streptococcus mitis'' *Group N - '' Lactococcus lactis'' *Group R & S - ''

Streptococcus suis ''Streptococcus suis'' is a peanut-shaped, Gram-positive bacterium, and an important pathogen of pigs. Endemic in nearly all countries with an extensive pig industry, ''S. suis'' is also a zoonotic disease, capable of transmission to humans from ...

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

References

{{Clinical microbiology techniques Bacteriology Microbiology techniques