II. Systemic Bacteriology | 2. Streptococcus pyogenes. Flashcards
I. Basics
1. What is Streptococcus taxonomy?
I. Basics
2. What are the 2 types of Grouping of streptococci?
- Lancefield serogrouping (cell wall polysaccharide)
- Based on hemolysis
I. Basics
3. How do we group streptococci by Lancefield serogrouping?
- Latex agglutination
- S. pyogenes = A (GAS)
- S. agalactiae = B (GBS)
- Enterococci = D
I. Basics
4. How do we group streptococci based on hemolysis?
- β-hemolytic: S. pyogenes, S. agalactiae
- α-hemolytic: S. pneumoniae, viridans streptococci
- non-hemolytic: enterococci
II. Streptococcus pyogenes
1. What is the Microscopic morphology of Streptococcus pyogenes?
– Gram-positive cocci, arranged in long chains
– ‚streptos’ in Greek = chain
II. Streptococcus pyogenes
2. What is the Colony morphology (cultivation) of Streptococcus pyogenes?
– small, pin-point colonies
– strong β-hemolysis
– fastidious! (requires blood agar)
III. S. pyogenes virulence factors
1. What are the 3 types of S. pyogenes virulence factor?
- Cell bound virulence factors
- Enzymes (invasion, spread)
- Toxins
III. S. pyogenes virulence factors
2. What are cell bound virulence factors by S. pyogenes?
- Capsule made of hyaluronic acid (!) – not antigenic!
- M protein
- F protein (fibronectin binding)
III. S. pyogenes virulence factors
3. What are Enzymes (invasion, spread) by S. pyogenes?
- streptokinase
- fibrin lysis (in heart attack!), lysing purulent foci - streptodornase (DNase)
- hyaluronidase
- ribonuclease
III. S. pyogenes virulence factors
4A. What are Toxins produced by S. pyogenes?
- hemolysins
- streptococcal pyrogenic exotoxins (SPEs) or erythrogenic toxins
III. S. pyogenes virulence factors - Toxins
4B. What are the types and features of hemolysins?
- streptolysin-S (β-hemolysis!, poor antigen)
- streptolysin-O (good antigen → ASO-titer!)
III. S. pyogenes virulence factors - Toxins
4B. What are the types and features of streptococcal pyrogenic exotoxins (SPEs) ?
streptococcal pyrogenic exotoxins (SPEs) or erythrogenic toxins
- especially SpeA, SpeB, SpeC
- skin symptoms of scarlet fever
- streptococcal toxic shock syndrome
- necrotizing fasciitis (=protease)
IV. S. pyogenes infections
1. What are the infections caused by S.pyogenes?
- Respiratory tract infections
- Skin infections
- Other severe, acute, pyogenic infections
- Scarlet fevers
- Post-streptococcal diseases
IV. S. pyogenes infections
2. What are the respiratory tracts infections caused by S. pyogenes?
- pharyngitis („Strep throat”) * tonsillitis follicularis
- otitismedia,sinusitis
- pneumonia
IV. S. pyogenes infections
3. What are the skin infections caused by S. pyogenes? (see the cards in answer and question desk)
IV. S. pyogenes infections
4. What are other severe, acute, pyogenic infections?
- meningitis
- puerperal fever
- streptococcal toxic shock syndrome (udden onset of shock, multi organ failure, high death rate)
IV. S. pyogenes infections
5. What are the features of Scarlet fever?
- rush all over the body
- carriage of toxin-producing S. pyogenes strain in the throat
IV. S. pyogenes infections
6. What are the features of Post-streptococcal diseases?
- immunological origin
- a few weeks after the acute infection
- rheumatic fever
- glomerulonephritis
- rheumatoid arthritis
V. Treatment and prevention of S. pyogenes
1. What is the treatment for S. pyogenes?
- penicillin !! (100% penicillin susceptibility)
- Chemoprophylaxis: penicillin in case of scarlet fever
V. Treatment and prevention of S. pyogenes
2. Do we have vaccine for S. pyogenes?
No vaccination
* vaccine development in early clinical phases
* based on M protein or other surface proteins
* hyaluronic acid capsule is not immunogenic
