II. Systemic Bacteriology | 2. Streptococcus pyogenes.

Question 1

I. Basics
1. What is Streptococcus taxonomy?

Answer 1

Question 2

I. Basics
2. What are the 2 types of Grouping of streptococci?

Answer 2

• Lancefield serogrouping (cell wall polysaccharide)
• Based on hemolysis

Question 3

I. Basics
3. How do we group streptococci by Lancefield serogrouping?

Answer 3

• Latex agglutination
• S. pyogenes = A (GAS)
• S. agalactiae = B (GBS)
• Enterococci = D

Question 4

I. Basics
4. How do we group streptococci based on hemolysis?

Answer 4

• β-hemolytic: S. pyogenes, S. agalactiae
• α-hemolytic: S. pneumoniae, viridans streptococci
• non-hemolytic: enterococci

Question 5

II. Streptococcus pyogenes
1. What is the Microscopic morphology of Streptococcus pyogenes?

Answer 5

– Gram-positive cocci, arranged in long chains
– ‚streptos’ in Greek = chain

Question 6

II. Streptococcus pyogenes
2. What is the Colony morphology (cultivation) of Streptococcus pyogenes?

Answer 6

– small, pin-point colonies
– strong β-hemolysis
– fastidious! (requires blood agar)

Question 7

III. S. pyogenes virulence factors
1. What are the 3 types of S. pyogenes virulence factor?

Answer 7

1. Cell bound virulence factors
2. Enzymes (invasion, spread)
3. Toxins

Question 8

III. S. pyogenes virulence factors
2. What are cell bound virulence factors by S. pyogenes?

Answer 8

1. Capsule made of hyaluronic acid (!) – not antigenic!
2. M protein
3. F protein (fibronectin binding)

Question 9

III. S. pyogenes virulence factors
3. What are Enzymes (invasion, spread) by S. pyogenes?

Answer 9

1. streptokinase
   - fibrin lysis (in heart attack!), lysing purulent foci
2. streptodornase (DNase)
3. hyaluronidase
4. ribonuclease

Question 10

III. S. pyogenes virulence factors
4A. What are Toxins produced by S. pyogenes?

Answer 10

1. hemolysins
2. streptococcal pyrogenic exotoxins (SPEs) or erythrogenic toxins

Question 11

III. S. pyogenes virulence factors - Toxins
4B. What are the types and features of hemolysins?

Answer 11

• streptolysin-S (β-hemolysis!, poor antigen)
• streptolysin-O (good antigen → ASO-titer!)

Question 12

III. S. pyogenes virulence factors - Toxins
4B. What are the types and features of streptococcal pyrogenic exotoxins (SPEs) ?

Answer 12

streptococcal pyrogenic exotoxins (SPEs) or erythrogenic toxins
- especially SpeA, SpeB, SpeC
- skin symptoms of scarlet fever
- streptococcal toxic shock syndrome
- necrotizing fasciitis (=protease)

Question 13

IV. S. pyogenes infections
1. What are the infections caused by S.pyogenes?

Answer 13

1. Respiratory tract infections
2. Skin infections
3. Other severe, acute, pyogenic infections
4. Scarlet fevers
5. Post-streptococcal diseases

Question 14

IV. S. pyogenes infections
2. What are the respiratory tracts infections caused by S. pyogenes?

Answer 14

• pharyngitis („Strep throat”) * tonsillitis follicularis
• otitismedia,sinusitis
• pneumonia

Question 15

IV. S. pyogenes infections
3. What are the skin infections caused by S. pyogenes? (see the cards in answer and question desk)

Answer 15

Question 16

IV. S. pyogenes infections
4. What are other severe, acute, pyogenic infections?

Answer 16

• meningitis
• puerperal fever
• streptococcal toxic shock syndrome (udden onset of shock, multi organ failure, high death rate)

Question 17

IV. S. pyogenes infections
5. What are the features of Scarlet fever?

Answer 17

• rush all over the body
• carriage of toxin-producing S. pyogenes strain in the throat

Question 18

IV. S. pyogenes infections
6. What are the features of Post-streptococcal diseases?

Answer 18

• immunological origin
• a few weeks after the acute infection
• rheumatic fever
• glomerulonephritis
• rheumatoid arthritis

Question 19

V. Treatment and prevention of S. pyogenes
1. What is the treatment for S. pyogenes?

Answer 19

• penicillin !! (100% penicillin susceptibility)
• Chemoprophylaxis: penicillin in case of scarlet fever

Question 20

V. Treatment and prevention of S. pyogenes
2. Do we have vaccine for S. pyogenes?

Answer 20

No vaccination
* vaccine development in early clinical phases
* based on M protein or other surface proteins
* hyaluronic acid capsule is not immunogenic