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Flashcards in Streptococci Deck (46):
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.

31

Treatment of NF?

Rapid antibiotic treatment with penacillin or clindamycin if they have a penicillin allergy

32

Streptococcal toxic shock presentation

Shock, sepsis, rash that blanches when pressure is applied. Not as common as staph aureus tss

33

Clinical diagnosis of group A strep toxic shock syndrome

Isolation of GAS from a clinically significant specimen and two or more of the following:
renal impairment
coagulopathy
Liver dysfunction
Acute respiratory distress
macular rash
soft tissue necrosis

34

Erythema marginatum

skin rash that is a sign of ARF

35

Subcutaneous nodules

Also a sign of ARF

36

AGN findings

edema, hypertension, hematuria, proteinuria, malaise, headache, back pain
Lab: Ig, C3

37

Group B strep

Beta hemolysis
Bile esculin synthesis, Bacitracin resistant...the 3 Bs

38

What is CAMP factor

A factor produced by Group B strep that synergizes with staph aureus hemolysin to create increased lysis of red cells

39

Group B strep used to be the predominant cause of what in infants?

septicemia and meningitis in infants

40

What is a sensitive test for Group B strep>

Bile Esculin Hydrolysis

41

CAMP test

You cross streak a potential GBS sample with staph aureus and look to see if its Beta Hydrolysis ring expands. Will separate GBS from GAS.

42

GBS virulent factor

Capsule...antiphagocytic of course

43

Adheisns

Alpha protein and fibrinogen binding proteins

44

Early onset GBS infection in neonates falls during what time period?

7 days or younger.
Includes septicemia, resp distress, meningitis

45

Late onset GBS in infants when?

2 weeks to 2 months

46

Viridans streptococci

oral strep, alpha hemolytic
distinguished from enterococci by inabiltiy to grow in 6.5 % nacl