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''Streptococcus pyogenes'' is a species of bacteria. Like most other streptococci, it is clinically important in human illness. It is an infrequent, but usually pathogenic, part of the skin flora. It is the sole species of Lancefield group A and is often called group A streptococcus (GAS), because it displays streptococcal group A antigen on its cell wall. Group A streptococcal infection can cause illness, which typically produces small zones of beta-hemolysis, a complete destruction of red blood cells. (A zone size of 2-3 mm is typical). It is thus also called group A (beta-hemolytic) streptococcus (GABHS). Like other cocci, streptococci are round bacteria. The name derives from the Greek word ''streptos'', meaning twisted chain, because streptococcal cells tend to link together in chains, which resemble a string of pearls when viewed under the microscope.〔(【引用サイトリンク】url=http://www.medterms.com/script/main/art.asp?articlekey=11270 )〕 Streptococci are catalase-negative and Gram-positive. ''S. pyogenes'' can be cultured on blood agar plates. Under ideal conditions, it has an incubation period of 1 to 3 days. An estimated 700 million GAS infections occur worldwide each year. While the overall mortality rate for these infections is 0.1%, over 650,000 of the cases are severe and invasive, and have a mortality rate of 25%.〔 〕 Early recognition and treatment are critical; diagnostic failure can result in sepsis and death. == Serotyping == In 1928, Rebecca Lancefield published a method for serotyping ''S. pyogenes'' based on its M protein, a virulence factor displayed on its surface. Later, in 1946, Lancefield described the serologic classification of ''S. pyogenes'' isolates based on their surface T antigen. Four of the 20 T antigens have been revealed to be pili, which are used by bacteria to attach to host cells. Over 220 M serotypes and about 20 T serotypes are known. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Streptococcus pyogenes」の詳細全文を読む スポンサード リンク
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