Streptococcus pyogenes

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  • Created by: Rose
  • Created on: 19-05-14 11:14
How do Streptococci grow?
In chains
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Staphylococci are gram ____
positive.
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Staphylococci are catalase _____
negative.
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Which media do we use to differentiate different types of Streptococci?
Blood agar
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What colour do β-haemolytic Streptococci appear on blood agar, and why?
Yellow, due to complete haemolysis
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S. pyogenes is a 'pyogenic' member of this group, what does that mean?
Pus producing
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What colour do α-haemolytic Streptococci appear on blood agar, and why?
Green, due to partial haemolysis
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Name an α-haemolytic Streptococci species
S. pneumoniae
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What is the name given to normal throat residing flora (α-haemolytic Strep)?
Viridans Streptococci
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What colour do What colour do γ-haemolytic Streptococci appear on blood agar, and why?-haemolytic Streptococci appear on blood agar, and why?
Blue-ish, due to no haemolysis
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γ-haemolytic Streptocci are a normal flora of ____ but can cause _____ infections
Throat; Hospital
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Lancefield Grouping: This groups bacteria based on?
Their cell wall polysaccharides (Type A, Type B, etc..). Use antibody/antigen reaction to identify.
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Lancefield Grouping testing is most useful for detecting...
Beta-haemolytic Streptococci
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Name one difference between S. aureus / S. pyogenes
S. aureus will grow on nutrient agar, S. pyogenes will not ; S. aureus 'pinhead' colonies, S.pyogenes 'pinpoint' colonies
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Name one similarity between S. pyogenes and S. aureus
Both are haemolytic
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Which test is best for differentiating between S. aureus and S. pyogenes, and why?
CATALASE test: S. aureus = Cat + ; S. pyogenes = Cat -
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* S. pyogenes infection *
* S. pyogenes infection *
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Which serious SSTI is quite unique to S. pyogenes?
Necrotising fasciitis
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Name 4 infections caused by S. pyogenes, excluding SSTI
Tonsilitis, Scarlet Fever, TSS, Bacteremia
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Is S. pyogenes infection usually endogenous or exogenous?
Exogenous
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What is usually the source of S. pyogenes?
Another human
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Mode of Transmission?
Resp. droplets e.g. in tonsilitis, or contact e.g. SSTI
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Antibodies against which protein seem to give host protection?
M-protein
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* Virulence Factors *
* Virulence Factors *
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Which surface protein helps S. pyogenes with adherence?
Surface 'F Protein'
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Which other factor helps with adherence?
Lipoteichoic acid
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Which protein, found on the surface of S. pyogenes, undergoes much variation and thus helps with immune evasion?
M-protein
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M-protein can bind to _____, activating ______
Fibrinogen; Neutrophils
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The _____ peptidase helps with immune evasion by ____
C5a; degrading the complement
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What else helps protect S. pyogenes from the immune system?
Capsule
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Which two enzymes help S. pyogenes spread?
Streptokinase & Hyaluronidase
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S. pyogenes produces ______ __toxins that are strain specific
Pyrogenic Exo(toxins)
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The pyrogenic A and C exotoxins act as?
Superantigens
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Exotoxin B is associated with?
Deep tissue infections e.g. Necrotising fasciitis
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Name two sequelae caused by S. pyogenes infection
Rheumatic fever/heart disease ; Acute glomerulonephritis
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* Antibacterial Therapy *
* Antibacterial Therapy *
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S. pyogenes is usually treated with ______
Penicillin (Beta lactam)
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S. aureus used to be treated with ______ but this is no longer used due to ______
Penicillin ; Antibiotic Resistance
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Now, S. aureus is treated with ______ or ______
Methicillin/Oxacillin
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Which rare species of the Streptococcus genus commonly colonises the ****** and can cause infections in newborns?
Streptococcus agalactiae
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S. epidermis and Viridans Streptococci are both normal flora of the skin and throat, respectively. However, they can cause hospital infections as they are often found on....
Medical equipment
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Other cards in this set

Card 2

Front

Staphylococci are gram ____

Back

positive.

Card 3

Front

Staphylococci are catalase _____

Back

Preview of the front of card 3

Card 4

Front

Which media do we use to differentiate different types of Streptococci?

Back

Preview of the front of card 4

Card 5

Front

What colour do β-haemolytic Streptococci appear on blood agar, and why?

Back

Preview of the front of card 5
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