Streptococcus pyogenes

Streptococcus pyogenes
S. pyogenes bacteria at 900x magnification
Scientific classification
Kingdom: Eubacteria
Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Species: S. pyogenes
Binomial name
Streptococcus pyogenes
Rosenbach 1884

Streptococcus pyogenes is a species of bacteria. These bacteria are aerobic and an extracellular bacterium, made up of non-motile and non-sporing cocci. Like [most} many other streptococci, it is clinically important in human illness. It is an infrequent, but usually pathogenic, part of the skin flora. It is the predominant species harboring the Lancefield group A antigen, and is often called group A streptococcus (GAS). However, both Streptococcus dysgalactiae and the Streptococcus anginosus group can possess group A antigen. Group A streptococci when grown on blood agar 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), and can make colonies greater than 5 mm in size. [1]

Like other cocci, streptococci are round bacteria. The name is derived from the Greek meaning pus(pyo)-forming(genes) chain(Strepto) of berries (coccus), because streptococcal cells tend to link together in chains of round cells (see image) and a number of infections caused by the bacteria, produce pus. Streptococci are catalase-negative and Gram-positive.[2] S. pyogenes can be cultured on blood agar plates. Under ideal conditions, it has an incubation period of 1 to 3 days.[3]

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%.[4] Early recognition and treatment are critical; diagnostic failure can result in sepsis and death.[5][6]

Method(s) of transmission

→ Contact with these surfaces can spread infections




In 1928, Rebecca Lancefield published a method for serotyping S. pyogenes based on its M protein,[8] a virulence factor displayed on its surface.[9] Later, in 1946, Lancefield described the serologic classification of S. pyogenes isolates based on their surface T-antigen.[10] Four of the 20 T-antigens have been revealed to be pili, which are used by bacteria to attach to host cells.[11] Over 220 M serotypes and about 20 T serotypes are known.

Virulence factors

S. pyogenes has several virulence factors that enable it to attach to host tissues, evade the immune response, and spread by penetrating host tissue layers.[12] A carbohydrate-based bacterial capsule composed of hyaluronic acid surrounds the bacterium, protecting it from phagocytosis by neutrophils.[2] In addition, the capsule and several factors embedded in the cell wall, including M protein, lipoteichoic acid, and protein F (SfbI) facilitate attachment to various host cells.[13] M protein also inhibits opsonization by the alternative complement pathway by binding to host complement regulators. The M protein found on some serotypes is also able to prevent opsonization by binding to fibrinogen.[2] However, the M protein is also the weakest point in this pathogen's defense, as antibodies produced by the immune system against M protein target the bacteria for engulfment by phagocytes. M proteins are unique to each strain, and identification can be used clinically to confirm the strain causing an infection.


All strains of S. pyogenes are polylysogenized, in that they carry one or more bacteriophage on their genomes.[14] Some of the phages may be defective, but in some cases active phage may compensate for defects in others.[15] In general, the genome of S. pyogenes strains isolated during disease are >90% identical, they differ by the phage they carry.[16]

Name Description
Streptolysin O An exotoxin, one of the bases of the organism's beta-hemolytic property, streptolysin O causes an immune response and detection of antibodies to it; antistreptolysin O (ASO) can be clinically used to confirm a recent infection.
Streptolysin S A cardiotoxic exotoxin, another beta-hemolytic component, not immunogenic and O2 stable: A potent cell poison affecting many types of cell including neutrophils, platelets, and subcellular organelles.
Streptococcal pyrogenic exotoxin A (SpeA) Superantigens secreted by many strains of S. pyogenes: This pyrogenic exotoxin is responsible for the rash of scarlet fever and many of the symptoms of streptococcal toxic shock syndrome, also known as toxic shock like syndrome(TSLS).
Streptococcal pyrogenic exotoxin C (SpeC)
Streptokinase Enzymatically activates plasminogen, a proteolytic enzyme, into plasmin, which in turn digests fibrin and other proteins
Hyaluronidase Hyaluronidase is widely assumed to facilitate the spread of the bacteria through tissues by breaking down hyaluronic acid, an important component of connective tissue. However, very few isolates of S. pyogenes are capable of secreting active hyaluronidase due to mutations in the gene that encode the enzyme. Moreover, the few isolates capable of secreting hyaluronidase do not appear to need it to spread through tissues or to cause skin lesions.[17] Thus, the true role of hyaluronidase in pathogenesis, if any, remains unknown.
Streptodornase Most strains of S. pyogenes secrete up to four different DNases, which are sometimes called streptodornase. The DNases protect the bacteria from being trapped in neutrophil extracellular traps (NETs) by digesting the NETs' web of DNA, to which are bound neutrophil serine proteases that can kill the bacteria.[18]
C5a peptidase C5a peptidase cleaves a potent neutrophil chemotaxin called C5a, which is produced by the complement system.[19] C5a peptidase is necessary to minimize the influx of neutrophils early in infection as the bacteria are attempting to colonize the host's tissue.[20] C5a peptidase, although required to degrade the neutrophil chemotaxin C5a in the early stages of infection, is not required for S. pyogenes to prevent the influx of neutrophils as the bacteria spread through the fascia.[21]
Streptococcal chemokine protease The affected tissue of patients with severe cases of necrotizing fasciitis are devoid of neutrophils.[22] The serine protease ScpC, which is released by S. pyogenes, is responsible for preventing the migration of neutrophils to the spreading infection. ScpC degrades the chemokine IL-8, which would otherwise attract neutrophils to the site of infection.[20][21]


The genome of different strains were sequenced (genome size is 1.8–1.9 Mbp)[23] encoding about 1700-1900 proteins (1700 in strain NZ131,[24][25] 1865 in strain MGAS5005[26][27]).


S. pyogenes is the cause of many important human diseases, ranging from mild superficial skin infections to life-threatening systemic diseases.[2] Infections typically begin in the throat or skin. The most striking sign is a strawberry-like rash. Examples of mild S. pyogenes infections include pharyngitis (strep throat) and localized skin infection (impetigo). Erysipelas and cellulitis are characterized by multiplication and lateral spread of S. pyogenes in deep layers of the skin. S. pyogenes invasion and multiplication in the fascia can lead to necrotizing fasciitis, a life-threatening condition requiring surgery.

Infections due to certain strains of S. pyogenes can be associated with the release of bacterial toxins. Throat infections associated with release of certain toxins lead to scarlet fever. Other toxigenic S. pyogenes infections may lead to streptococcal toxic shock syndrome, which can be life-threatening.[2]

S. pyogenes can also cause disease in the form of postinfectious "nonpyogenic" (not associated with local bacterial multiplication and pus formation) syndromes. These autoimmune-mediated complications follow a small percentage of infections and include rheumatic fever and acute postinfectious glomerulonephritis. Both conditions appear several weeks following the initial streptococcal infection. Rheumatic fever is characterised by inflammation of the joints and/or heart following an episode of streptococcal pharyngitis. Acute glomerulonephritis, inflammation of the renal glomerulus, can follow streptococcal pharyngitis or skin infection.

This bacterium remains acutely sensitive to penicillin. Failure of treatment with penicillin is generally attributed to other local commensal organisms producing β-lactamase, or failure to achieve adequate tissue levels in the pharynx. Certain strains have developed resistance to macrolides, tetracyclines, and clindamycin.



Many S. pyogenes proteins have unique properties, which have been harnessed in recent years to produce a highly specific "superglue"[28][29] and a route to enhance the effectiveness of antibody therapy.[30]

Genome editing

The CRISPR system from this organism that is used to recognize and destroy DNA from invading viruses, stopping the infection, was appropriated in 2012 for use as a genome-editing tool that could potentially alter any piece of DNA and later RNA.[31]

See also


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  3. Streptococcal Pharyngitis, archived from the original on May 13, 2012
  4. Aziz RK, Kansal R, Aronow BJ, Taylor WL, Rowe SL, Kubal M, Chhatwal GS, Walker MJ, Kotb M (2010). Ahmed N, ed. "Microevolution of Group A Streptococci In Vivo: Capturing Regulatory Networks Engaged in Sociomicrobiology, Niche Adaptation, and Hypervirulence". PLoS ONE. 5 (4): e9798. doi:10.1371/journal.pone.0009798. PMC 2854683Freely accessible. PMID 20418946. Retrieved 2011-08-12.
  5. Jim Dwyer (July 11, 2012). "An Infection, Unnoticed, Turns Unstoppable". The New York Times. Retrieved July 12, 2012.
  6. Jim Dwyer (July 18, 2012). "After Boy's Death, Hospital Alters Discharging Procedures". The New York Times. Retrieved July 19, 2012.
  8. Pignanelli S, Brusa S, Pulcrano G, Catania MR, Cocchi E, Lanari M (2015). "A rare case of infant sepsis due to the emm-89 genotype of Group A Streptococcus within a community-acquired cluster". New Microbiol (38): 589–92. PMID 16223875.
  9. Lancefield RC (1928). "The antigenic complex of Streptococcus hemolyticus". J Exp Med. 47 (1): 9–10. doi:10.1084/jem.47.1.91.
  10. Lancefield RC, Dole VP (1946). "The properties of T antigen extracted from group A hemolytic streptococci". J Exp Med. 84 (5): 449–71. doi:10.1084/jem.84.5.449. PMC 2135665Freely accessible. PMID 19871581.
  11. Mora M, Bensi G, Capo S, Falugi F, Zingaretti C, Manetti AG, Maggi T, Taddei AR, Grandi G, Telford JL (2005). "Group A Streptococcus produce pilus-like structures containing protective antigens and Lancefield T antigens". Proc Natl Acad Sci USA. 102 (43): 15641–6. doi:10.1073/pnas.0507808102. PMC 1253647Freely accessible. PMID 16223875.
  12. Patterson MJ (1996). Baron S; et al., eds. Streptococcus. In: Baron's Medical Microbiology (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1.
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  17. Starr CR, Engleberg NC (2006). "Role of Hyaluronidase in Subcutaneous Spread and Growth of Group A Streptococcus". Infect Immun. 74 (1): 40–8. doi:10.1128/IAI.74.1.40-48.2006. PMC 1346594Freely accessible. PMID 16368955.
  18. Buchanan JT, Simpson AJ, Aziz RK, Liu GY, Kristian SA, Kotb M, Feramisco J, Nizet V (2006). "DNase expression allows the pathogen group A Streptococcus to escape killing in neutrophil extracellular traps". Curr Biol. 16 (4): 396–400. doi:10.1016/j.cub.2005.12.039. PMID 16488874.
  19. Wexler DE, Chenoweth DE, Cleary PP (1985). "Mechanism of action of the group A streptococcal C5a inactivator". Proc Natl Acad Sci USA. 82 (23): 8144–8. doi:10.1073/pnas.82.23.8144. PMC 391459Freely accessible. PMID 3906656.
  20. 1 2 Ji Y, McLandsborough L, Kondagunta A, Cleary PP (1996). "C5a peptidase alters clearance and trafficking of group A streptococci by infected mice". Infect Immun. 64 (2): 503–10. PMC 173793Freely accessible. PMID 8550199.
  21. 1 2 Hidalgo-Grass C, Mishalian I, Dan-Goor M, Belotserkovsky I, Eran Y, Nizet V, Peled A, Hanski E (2006). "A streptococcal protease that degrades CXC chemokines and impairs bacterial clearance from infected tissues". EMBO J. 25 (19): 4628–37. doi:10.1038/sj.emboj.7601327. PMC 1589981Freely accessible. PMID 16977314.
  22. Hidalgo-Grass C, Dan-Goor M, Maly A, Eran Y, Kwinn LA, Nizet V, Ravins M, Jaffe J, Peyser A, Moses AE, Hanski E (2004). "Effect of a bacterial pheromone peptide on host chemokine degradation in group A streptococcal necrotising soft-tissue infections". Lancet. 363 (9410): 696–703. doi:10.1016/S0140-6736(04)15643-2. PMID 15001327.
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  24. "Streptococcus pyogenes NZ131".
  25. McShan, W. M.; Ferretti, J. J.; Karasawa, T; Suvorov, A. N.; Lin, S; Qin, B; Jia, H; Kenton, S; Najar, F; Wu, H; Scott, J; Roe, B. A.; Savic, D. J. (2008). "Genome sequence of a nephritogenic and highly transformable M49 strain of Streptococcus pyogenes". Journal of Bacteriology. 190 (23): 7773–85. doi:10.1128/JB.00672-08. PMC 2583620Freely accessible. PMID 18820018.
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  27. "Streptococcus pyogenes MGAS5005".
  28. "Flesh-eating bacteria inspire superglue - University of Oxford".
  29. Zakeri B, Fierer JO, Celik E, Chittock EC, Schwarz-Linek U, Moy VT, Howarth M (2012). "Peptide tag forming a rapid covalent bond to a protein, through engineering a bacterial adhesin". Proceedings of the National Academy of Sciences. 109 (12): E690–7. doi:10.1073/pnas.1115485109. PMC 3311370Freely accessible. PMID 22366317.
  30. Baruah K, Bowden TA, Krishna BA, Dwek RA, Crispin M, Scanlan CN (2012). "Selective Deactivation of Serum IgG: A General Strategy for the Enhancement of Monoclonal Antibody Receptor Interactions". Journal of Molecular Biology. 420 (1–2): 1–7. doi:10.1016/j.jmb.2012.04.002. PMC 3437440Freely accessible. PMID 22484364.
  31. Zimmer, Carl (2016-06-03). "Scientists Find Form of Crispr Gene Editing With New Capabilities". The New York Times. ISSN 0362-4331. Retrieved 2016-06-10.

Further reading

External links

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