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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.
Group A streptococcal infections are a number of infections with Streptococcus pyogenes, a group A streptococcus (GAS). [1] S. pyogenes is a species of beta-hemolytic Gram-positive bacteria that is responsible for a wide range of infections that are mostly common and fairly mild. If the bacteria enters the bloodstream, the infection can become ...
Main Streptococcus groups are included as "Strep." at bottom left. In clinical practice, the most common groups of Streptococcus can be distinguished by simple bench tests, such as the PYR test for group A streptococcus. There are also latex agglutination kits which can distinguish each of the main groups seen in clinical practice.
Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by Streptococcus pyogenes, a gram-positive, group A streptococcus. [9] [10] Common symptoms include fever, sore throat, red tonsils, and enlarged lymph nodes in the front of the neck.
[2] [7] An additional method used to identify B-hemolytic streptococci is the PYR test, which is primarily used in distinguishing S. pyogenes from other B-hemolytic strains by testing for the presence of pyrrolidonyl aminopeptidase. [2] Both the Lancefield antigen grouping sera and PYR test are widely available for commercial usage.
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. [2]
Group A Streptococcus pyogenes is a bacterium that can lead to common infections, including strep throat and impetigo, but is also responsible for life-threatening infections. [ 31 ] [ 32 ] During infection, GrpE helps streptococcus bacteria adhere to pharyngeal epithelial cells . [ 32 ]
M protein is strongly anti-phagocytic and is the major virulence factor for group A streptococci (Streptococcus pyogenes). It binds to serum factor H, destroying C3-convertase and preventing opsonization by C3b. However plasma B cells can generate antibodies against M protein which will help in opsonization and further the destruction of the ...