Streptococci

Question 1

The three most important human pathogens

Answer 1

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

Question 2

Are Strep facultative anaerobes?

Answer 2

Yes

Question 3

What color is Alpha hemolysis on a blood agar plate?

Answer 3

Green

Question 4

What color is Beta Hemolysis

Answer 4

Clear

Question 5

What about gamma hemolysis?

Answer 5

This is almost non-hemolytic.

Question 6

What hemolysis pattern do AN and B follow?

Answer 6

Beta hemolytic

Question 7

S. pneumoniae?

Answer 7

Alpha hemolytic

Question 8

Catalase negative or positive?

Answer 8

Negative…this differentiates them from staph

Question 9

Oxidase negative or positive?

Answer 9

Negative

Question 10

What is the largest Strep A burden in the world?

Answer 10

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

Question 11

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

Answer 11

Skin infections generally

Question 12

ARF and AGN are immune mediated diseases?

Answer 12

Yes

Question 13

Beta hemolysis due to what enzymes?

Answer 13

Streptolysin O and streptolysin S

Question 14

Streptolysin S is oxygen stable

Answer 14

true

Question 15

SLO is oxygen stable

Answer 15

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

Question 16

Group A virulence factors

Answer 16

Hyaluronic acid capsule
M Protein
Lipoteichoic acid

Question 17

What is significant about the hyaluronic acid capsule

Answer 17

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

Question 18

M protein significance?

Answer 18

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.

Question 19

LTA?

Answer 19

adhesin, PAMP, and defense against antimicrobial peptides

Question 20

What are streptococcal pyrogenic exotoxin A?

Answer 20

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

Question 21

Treatment of Streptococcal pharyngitis with penicillin reduces the risk of

Answer 21

ARF

Question 22

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

Answer 22

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

Question 23

Puerperal fever?

Answer 23

streptococcal infection that frequently developed after giving birth.

Question 24

Group A strep Impetigo

Answer 24

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

Question 25

What can a GAS skin infection like Impetigo turn into?

Answer 25

Glomerulonephritis

Question 26

What is Ecthyma

Answer 26

deep impetigo...pus filled center.

Question 27

erysipelas

Answer 27

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

Question 28

Cellulitis

Answer 28

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

Question 29

Streptococcal toxic shock and necrotizing fascitis

Answer 29

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

Question 30

Major virulence factors in necrotizing fascitis?

Answer 30

Streptococcal pyrogenic exotoxins.

Question 31

Treatment of NF?

Answer 31

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

Question 32

Streptococcal toxic shock presentation

Answer 32

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

Question 33

Clinical diagnosis of group A strep toxic shock syndrome

Answer 33

``` 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 ```

Question 34

Erythema marginatum

Answer 34

skin rash that is a sign of ARF

Question 35

Subcutaneous nodules

Answer 35

Also a sign of ARF

Question 36

AGN findings

Answer 36

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

Question 37

Group B strep

Answer 37

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

Question 38

What is CAMP factor

Answer 38

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

Question 39

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

Answer 39

septicemia and meningitis in infants

Question 40

What is a sensitive test for Group B strep>

Answer 40

Bile Esculin Hydrolysis

Question 41

CAMP test

Answer 41

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.

Question 42

GBS virulent factor

Answer 42

Capsule...antiphagocytic of course

Question 43

Adheisns

Answer 43

Alpha protein and fibrinogen binding proteins

Question 44

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

Answer 44

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

Question 45

Late onset GBS in infants when?

Answer 45

2 weeks to 2 months

Question 46

Viridans streptococci

Answer 46

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