Streptococci: GAS Flashcards
1
Q
Non-suppurative sequelae from S.pyogenes
A
- Acute Rheumatic Fever (ARF): inflammation of heart and joints (autoimmune repsonse)
- Acute Glomerulonephritis (immune complex deposits)
2
Q
Carriage is key for maintenance and transmission
A
- Asymptomatic carriage is high!
- Nasopharyngeal, mucosa, skin, vaginal
3
Q
S.pyogenes surviving in salvia
A
- Amylase to gain carbohydrates
4
Q
Virulence factors of GAS
A
- Fibronectin binding proteins (adhesion)
- Catalytic enzymes
- Pilus (antigenic variation)
- M protein (entry)
- Acid capsule (molecular mimicry)
- Superantigenic exotoxins
- Lipoteichoic acid (adhesion)
5
Q
M protein virulence features:
A
- Resist complement (anti-phagocytic)
- Attachment to keratinocytes
- Aggregation at epithelial cells
- Sequence and length = strain differentials
- Antigenic variation
6
Q
Key GAS adherence features
A
- 2 step process (LTA and M protein)
- LTA weak attachment and long attachment by pili and fibronectin binding proteins
- M protein higher affinity attachment lots of adhesins = bacterial entry
7
Q
Toxic Shock Syndrome and GAS
A
- Severe infections, hyper-inflammatory state
- Mediated by superantigens
- Vascular leakage
- Coagulation
- Circulatory collapse
- Organ failure
- Death
8
Q
What is a superantigen?
A
Strong antigen causes non-specific T cell activation = mass response
9
Q
Treatment for S.pyogenes
A
Penicillin sensitive
10
Q
Vaccine possibility?
A
- Limited Ags, not all can be used for vaccine
- Could target M protein but >200 types
