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Flashcards in Streptococci Deck (46)
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1

The three most important human pathogens

Strep pyogenes (A), Strep agalactiae (B), Strep pnumonia

2

Are Strep facultative anaerobes?

Yes

3

What color is Alpha hemolysis on a blood agar plate?

Green

4

What color is Beta Hemolysis

Clear

5

What about gamma hemolysis?

This is almost non-hemolytic.

6

What hemolysis pattern do AN and B follow?

Beta hemolytic

7

S. pneumoniae?

Alpha hemolytic

8

Catalase negative or positive?

Negative...this differentiates them from staph

9

Oxidase negative or positive?

Negative

10

What is the largest Strep A burden in the world?

Acute Rheumatic Fever which follows pharyngitis. Can lead to Rheumatic heart disease.

11

Acute glomerulonephrits is a sequela of strep that follows what type of infections

Skin infections generally

12

ARF and AGN are immune mediated diseases?

Yes

13

Beta hemolysis due to what enzymes?

Streptolysin O and streptolysin S

14

Streptolysin S is oxygen stable

true

15

SLO is oxygen stable

False. SLO is oxygen unstable so you have to grow it below the surface of the agar to see its activity

16

Group A virulence factors

Hyaluronic acid capsule
M Protein
Lipoteichoic acid

17

What is significant about the hyaluronic acid capsule

It is antiphagocytic and the structure of the hyaluronic acid is identical to the structure of human hyaluronic acid meaning that there are no antibodies formed against it

18

M protein significance?

Binds to fibronectin and other host proteins which hides the bacteria from the immune system and makes it antiphagocytic. It is the serological marker for Group A strep.

19

LTA?

adhesin, PAMP, and defense against antimicrobial peptides

20

What are streptococcal pyrogenic exotoxin A?

Superantigens...massively activate the immune system and create cytokine storms leading to sepsis

21

Treatment of Streptococcal pharyngitis with penicillin reduces the risk of

ARF

22

Can you get strep throat from strains with identical M proteins more than once?

Nope. You develop a type specific M- antibody to protect against the recurrence of infection with the infecting serotype.

23

Puerperal fever?

streptococcal infection that frequently developed after giving birth.

24

Group A strep Impetigo

superficial purulent skin infection
Most common in children
Often follows insect bites
weeping vesicles that form honey colored crust

25

What can a GAS skin infection like Impetigo turn into?

Glomerulonephritis

26

What is Ecthyma

deep impetigo...pus filled center.

27

erysipelas

a form of streptococcal cellulitis, charactertized by red erythema, edema, pain, fever, lymphadenopathy

28

Cellulitis

Acute inflammatory condition of the skin. Deeper than ecthyma or erysipelas. Pain edema, swelling, heat,

29

Streptococcal toxic shock and necrotizing fascitis

Infection begins inside. Just looks like a bruise, Rapid necrosis of up to an inch an hour. Flu-like, edema, extreme pain way out of proportion to the lesion appearance

30

Major virulence factors in necrotizing fascitis?

Streptococcal pyrogenic exotoxins.