Editing Streptococcus pyogenes (section)

=== Serotyping ===

In 1928, [[Rebecca Lancefield]] published a method for serotyping ''S. pyogenes'' based on its cell-wall polysaccharide,<ref name=Pignanelli_2015>{{cite journal | vauthors = Pignanelli S, Brusa S, Pulcrano G, Catania MR, Cocchi E, Lanari M | title = A rare case of infant sepsis due to the emm-89 genotype of Group A Streptococcus within a community-acquired cluster | journal = The New Microbiologica | volume = 38 | issue = 4 | pages = 589–592 | date = October 2015 | pmid = 26485019 }}</ref> a [[virulence]] factor displayed on its surface.<ref name=Lancefield_1928>{{cite journal | vauthors = Lancefield RC | title = The Antigenic Complex of Streptococcus Hæmolyticus | journal = The Journal of Experimental Medicine | volume = 47 | issue = 1 | pages = 91–103 | date = January 1928 | pmid = 19869404 | pmc = 2131344 | doi = 10.1084/jem.47.1.91 }}</ref> Later, in 1946, Lancefield described the serologic classification of ''S. pyogenes'' isolates based on components of their surface [[pilus|pili]] (known as the T-antigen)<ref name=Lancefield_1946>{{cite journal | vauthors = Lancefield RC, Dole VP | title = The Properties of T Antigens Extracted from Group a Hemolytic Streptococci | journal = The Journal of Experimental Medicine | volume = 84 | issue = 5 | pages = 449–471 | date = October 1946 | pmid = 19871581 | pmc = 2135665 | doi = 10.1084/jem.84.5.449 }}</ref>  which are used by bacteria to attach to host cells.<ref name=Mora_2005>{{cite journal | vauthors = Mora M, Bensi G, Capo S, Falugi F, Zingaretti C, Manetti AG, Maggi T, Taddei AR, Grandi G, Telford JL | display-authors = 6 | title = Group A Streptococcus produce pilus-like structures containing protective antigens and Lancefield T antigens | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 102 | issue = 43 | pages = 15641–15646 | date = October 2005 | pmid = 16223875 | pmc = 1253647 | doi = 10.1073/pnas.0507808102 | doi-access = free | bibcode = 2005PNAS..10215641M }}</ref> As of 2016, a total of 120 [[M protein (Streptococcus)|M proteins]] have been identified. These M proteins are encoded by 234 type ''emm'' genes with greater than 1,200 alleles.<ref name="epidemiology"/>