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==Pathophysiology==
==Pathophysiology==
===Transmission===
Group A streptococcal infection can be transmitted by the following:<ref name="pmid27312939">{{cite journal| author=Brouwer S, Barnett TC, Rivera-Hernandez T, Rohde M, Walker MJ| title=Streptococcus pyogenes adhesion and colonization. | journal=FEBS Lett | year= 2016 | volume= 590 | issue= 21 | pages= 3739-3757 | pmid=27312939 | doi=10.1002/1873-3468.12254 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27312939  }} </ref>
*Direct inoculation transmission
*Infected airborne droplets


===Virulence factors===
Group A streptococcus are responsible for various diseases ranging from mild to life threatening cases. The bacteria depends mainly on many virulence factors which are responsible for the pathogenesis of the infections.<ref name="pmid27312939">{{cite journal| author=Brouwer S, Barnett TC, Rivera-Hernandez T, Rohde M, Walker MJ| title=Streptococcus pyogenes adhesion and colonization. | journal=FEBS Lett | year= 2016 | volume= 590 | issue= 21 | pages= 3739-3757 | pmid=27312939 | doi=10.1002/1873-3468.12254 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27312939  }} </ref>


{| class="wikitable"
!Virulence factors
!Mechanism of action
|-
|M - protein
|
* The most important virulence factor.
* It prevents the phagocytosis of the bacteria by binding to the fibrinogen and prevents binding the complement to the bacterial cell wall.   
|-
|Streptolysin O and S
|
* Streptolysin O works on killing the differecnt cells like the neutrophils, platelets and the sub-cellular organelles.
|-
|Streptococcal pyrogenic exotoxins A and C
|
* SpeA and SpeC are superantigens secreted by many strains of ''S. pyogenes''.  These pyrogenic exotoxins are responsible for the [[rash]] of [[scarlet fever]] and many of the symptoms of streptococcal [[toxic shock syndrome]].
|-
|Streptokinase
|
* Enzymatically activates [[plasminogen]] which is a proteolytic enzyme into [[plasmin]] which in turn digests [[fibrin]] and other proteins.
|-
|Hyalourinidase
|
* It helps the bacteria to spread through the tissue by destroying the hyaluronic acid which is a connective tissue component.<ref name=Starr_2006>{{cite journal |author=Starr C, Engleberg N |title=Role of hyaluronidase in subcutaneous spread and growth of group A streptococcus |journal=Infect Immun |volume=74 |issue=1 |pages=40-8 |year=2006 |id=PMID 16368955}}</ref>
|-
|Streptodornase
|
* Most strains of ''S. pyogenes'' secrete up to four different [[DNase]]s, which are sometimes called ''streptodornase''. The DNases protect the bacteria from being trapped in [[neutrophil extracellular traps]] (NETs) by digesting the NET's web of DNA, to which are bound [[neutrophil]] [[serine protease]]s that can kill the bacteria.<ref name=Buchanan_2006>{{cite journal |author=Buchanan J, Simpson A, Aziz R, Liu G, Kristian S, Kotb M, Feramisco J, Nizet V |title=DNase expression allows the pathogen group A Streptococcus to escape killing in neutrophil extracellular traps |journal=Curr Biol |volume=16 |issue=4 |pages=396-400 |year=2006 |id=PMID 16488874}}</ref>
|-
|[[C5a]] [[peptidase]]
|
*C5a peptidase cleaves a potent [[neutrophil]] chemotaxin called [[C5a]], which is produced by the complement system.<ref name=Wexler_1985>{{cite journal |author=Wexler D, Chenoweth D, Cleary P |title=Mechanism of action of the group A streptococcal C5a inactivator |journal=Proc Natl Acad Sci U S A |volume=82 |issue=23 |pages=8144-8 |year=1985 |id=PMID 3906656}}</ref>  C5a peptidase is necessary to minimize the influx of neutrophils early in infection as the bacteria are attempting to colonize the host's tissue.<ref name="Ji 1996">{{cite journal |author=Ji Y, McLandsborough L, Kondagunta A, Cleary P |title=C5a peptidase alters clearance and trafficking of group A streptococci by infected mice |journal=Infect Immun |volume=64 |issue=2 |pages=503-10 |year=1996 |id=PMID 8550199}}</ref>.
|-
|Streptococcal chemokine protease
|
*The affected tissue of patients with severe cases of [[necrotizing fasciitis]] are devoid of [[neutrophil]]s.<ref name=Hidalgo-Grass_2004>{{cite journal |author=Hidalgo-Grass C, Dan-Goor M, Maly A, Eran Y, Kwinn L, Nizet V, Ravins M, Jaffe J, Peyser A, Moses A, Hanski E |title=Effect of a bacterial pheromone peptide on host chemokine degradation in group A streptococcal necrotising soft-tissue infections |journal=Lancet |volume=363 |issue=9410 |pages=696-703 |year=2004 |id=PMID 15001327}}</ref>.  The [[serine protease]] ScpC, which is released by ''S. pyogenes'', is responsible for preventing the migration of neutrophils to the spreading infection.<ref name="Hidalgo-Grass 2006">{{cite journal |author=Hidalgo-Grass C, Mishalian I, Dan-Goor M, Belotserkovsky I, Eran Y, Nizet V, Peled A, Hanski E |title=A streptococcal protease that degrades CXC chemokines and impairs bacterial clearance from infected tissues |journal=EMBO J |volume=25 |issue=19 |pages=4628-37 |year=2006 |id=PMID 16977314}}</ref>  ScpC degrades the [[chemokine]] [[IL-8]], which would otherwise attract [[neutrophil]]s to the site of infection.  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]].<ref name="Ji 1996"/><ref name="Hidalgo-Grass 2006"/>
|}


==References==
{{Reflist|2}}


==References==
==References==

Revision as of 21:43, 29 May 2017

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Group A streptococcal infection Microchapters

Home

Overview

Classification

Impetigo
Strep throat
Rheumatic heart disease
Poststreptococcal glomerulonephritis
Sinusitis
Scarlet fever
Tonsilitis
Otitis
Osteomyelitis
Meningitis
Brain abscess
Endometritis
Cellulitis
Erysipelas
Toxic Shock Syndrome

Pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Classification

Group A streptcocci or streptoccus pyogenes causes a wide range of diseases in many organs in the body. It is important to classify the infections caused by the bacteria in order to understand every disease separately. Classification of the group A streptococcal infections will be based on the pathogenesis of the infection and the organ infected. According to the pathogenesis of the infection, they can be classified into pyogenic, toxogenic or immunogenic infections. Based on the location, the streptococcus pyogenes affects the lungs, ear, nose, throat, blood, female genital system and the central nervous system.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Group A streptococcal infections
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pathogenesis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Organ based
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pyogenic
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Toxogenic
 
 
 
 
 
 
 
Immunogenic
 
 
 
 
 
 
 
Lungs
 
 
 
 
 
Ear, nose and throat
 
 
 
 
 
Bone
 
 
Blood
 
 
 
Female genital system
 
 
 
 
 
Brain
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pneumonia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Osteomyelitis
 
 
Bacteremia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pharyngitis (Strep throat)
 
Cellulitis
 
Impetigo
 
Erysipellas
 
 
 
Scarlet fever
 
Toxic shock like syndrome
 
Necrotizing fascitis
 
Rheumatic fever
 
Glomerulonephritis
 
 
 
 
 
 
 
 
 
Sinusitis
 
Tonsilitis
 
Otitis media
 
 
 
 
 
 
 
 
 
 
Postpartum endometritis
 
Vaginitis
 
Meningitis
 
Brain abscess

Pathophysiology

Transmission

Group A streptococcal infection can be transmitted by the following:[1]

  • Direct inoculation transmission
  • Infected airborne droplets

Virulence factors

Group A streptococcus are responsible for various diseases ranging from mild to life threatening cases. The bacteria depends mainly on many virulence factors which are responsible for the pathogenesis of the infections.[1]

Virulence factors Mechanism of action
M - protein
  • The most important virulence factor.
  • It prevents the phagocytosis of the bacteria by binding to the fibrinogen and prevents binding the complement to the bacterial cell wall.
Streptolysin O and S
  • Streptolysin O works on killing the differecnt cells like the neutrophils, platelets and the sub-cellular organelles.
Streptococcal pyrogenic exotoxins A and C
  • SpeA and SpeC are superantigens secreted by many strains of S. pyogenes. These pyrogenic exotoxins are responsible for the rash of scarlet fever and many of the symptoms of streptococcal toxic shock syndrome.
Streptokinase
  • Enzymatically activates plasminogen which is a proteolytic enzyme into plasmin which in turn digests fibrin and other proteins.
Hyalourinidase
  • It helps the bacteria to spread through the tissue by destroying the hyaluronic acid which is a connective tissue component.[2]
Streptodornase
C5a peptidase
  • C5a peptidase cleaves a potent neutrophil chemotaxin called C5a, which is produced by the complement system.[4] C5a peptidase is necessary to minimize the influx of neutrophils early in infection as the bacteria are attempting to colonize the host's tissue.[5].
Streptococcal chemokine protease
  • The affected tissue of patients with severe cases of necrotizing fasciitis are devoid of neutrophils.[6]. The serine protease ScpC, which is released by S. pyogenes, is responsible for preventing the migration of neutrophils to the spreading infection.[7] ScpC degrades the chemokine IL-8, which would otherwise attract neutrophils to the site of infection. 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.[5][7]

References

  1. ↑ 1.0 1.1 Brouwer S, Barnett TC, Rivera-Hernandez T, Rohde M, Walker MJ (2016). "Streptococcus pyogenes adhesion and colonization". FEBS Lett. 590 (21): 3739–3757. doi:10.1002/1873-3468.12254. PMID 27312939.
  2. ↑ Starr C, Engleberg N (2006). "Role of hyaluronidase in subcutaneous spread and growth of group A streptococcus". Infect Immun. 74 (1): 40–8. PMID 16368955.
  3. ↑ Buchanan J, Simpson A, Aziz R, Liu G, Kristian S, 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. PMID 16488874.
  4. ↑ Wexler D, Chenoweth D, Cleary P (1985). "Mechanism of action of the group A streptococcal C5a inactivator". Proc Natl Acad Sci U S A. 82 (23): 8144–8. PMID 3906656.
  5. ↑ 5.0 5.1 Ji Y, McLandsborough L, Kondagunta A, Cleary P (1996). "C5a peptidase alters clearance and trafficking of group A streptococci by infected mice". Infect Immun. 64 (2): 503–10. PMID 8550199.
  6. ↑ Hidalgo-Grass C, Dan-Goor M, Maly A, Eran Y, Kwinn L, Nizet V, Ravins M, Jaffe J, Peyser A, Moses A, 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. PMID 15001327.
  7. ↑ 7.0 7.1 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. PMID 16977314.

References


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