Streptococci

Question 1

Gamma hemolysis is ______________.

Answer 1

no hemolysis

Question 2

Incomplete hemolysis is also called ______________.

Answer 2

alpha hemolysis

Question 3

Complete hemolysis is also referred to as _____________.

Answer 3

beta hemolysis

Question 4

____________ are an offshoot of Streptococci and were formerly called group D Streptococci.

Answer 4

Enterococcus

Question 5

What virulence factor determines the strain of Streptococcus pyogenes?

Answer 5

The M factor (like the M on the baker’s hat)

It is anti-phagocytic.

Question 6

Like Neisseria, group A Streptococci have ________.

Answer 6

pili

Question 7

Why would bacteria need a DNAse?

Answer 7

Because DNA inhibits the mobility of bacteria –it is what makes pus gooey –so digesting it allows bacteria to spread.

Question 8

What are current AAP guidelines regarding testing for Strep.?

Answer 8

If the rapid antigen test comes back negative, then place one sample on a blood agar.

Question 9

Rheumatic heart disease is a _____________ Streptococcal infection.

Answer 9

non-suppurative (meaning S. pyogenes will not be cultured on blood agar)

Question 10

Erysipelas is more ____________ than cellulitis.

Answer 10

superficial

Question 11

Given what this lecturer told you about the kinds of infections caused by Streptococcus, why does it make sense that S. pyogenes is the bacterium that produces streptolysin?

Answer 11

Because S. pyogenes spreads, and streptolysin helps spread.

Question 12

PSGN and RHF are both caused by ____________ strains of GAS.

Answer 12

non-invasive

Question 13

Why is clindamycin recommended for severe Streptococcal infections?

Answer 13

Because clindamycin inhibits protein synthesis, which is important in severe infections because bactericidal antibiotics can cause the sudden release of toxins.

Question 14

True or false: M protein prevents phagocytosis of Streptococcus agalactiae.

Answer 14

False. GBS lacks M protein, but it still has the anti-phagocytic polysaccharide capsule.

Question 15

Streptococcus milleri has a distinct smell: ______________.

Answer 15

butterscotch

Question 16

Which Streptococcus strain is Camp-test positive?

Answer 16

Group B Strep (agalactiae)

Question 17

Which Streptococcus strain grows in 6.5% NaCl?

Answer 17

Enterococcus (all types)

Question 18

What does Lancefield testing test for?

Answer 18

Group-specific carbohydrates

Question 19

What Lancefield group does S. pyogenes fall in?

Answer 19

C-carbohydrate (group A)

Question 20

What kind of protein is M protein?

Answer 20

Fine fimbriae that help lipoteichoic acid bind to epithelium (strains lacking this are avirulent)

Question 21

Antibodies to _______________ provide immunity to Streptococcus pyogenes.

Answer 21

M protein

Note: this confers lifelong immunity, but there are so many subtypes that you can always get infected with more strains of S. pyogenes.

Question 22

In addition to serving adhesive properties, M protein also _________________.

Answer 22

is antiphagocytic

Question 23

What is the capsule around Streptococcus pyogenes composed of?

Answer 23

Hyaluronic acid (remember the Hot Apple Pie from Sketchy)

Question 24

Why does Streptococcus produce better hemolysis when inserted deep into the blood agar?

Answer 24

Because streptolysin O –the toxin that hemolyzes RBCs –is destroyed by oxygen

Question 25

What is the name of the family of exotoxins that cause scarlet fever, necrotizing fasciitis, and toxic shock?

Answer 25

Pyrogenic exotoxins A-C

Question 26

Antibiotic therapy for Streptococcal pharyngitis is primarily aimed at preventing ______________.

Answer 26

acute rheumatic fever

Question 27

What are the symptoms of scarlet fever?

Answer 27

Strawberry tongue
Fever
Red rash

Question 28

Acute rheumatic fever occurs about __________ after an infection with Streptococcus pyogenes.

Answer 28

3-6 weeks

Question 29

What are two big distinctions between the causes of PSGN and ARF?

Answer 29

ARF is only caused by pharyngitis and is preventable with antibiotics, while PSGN can be caused by impetigo or pharyngitis and is not preventable with antibiotics.

Question 30

Group B Streptococci do not have ______________, found in S. pyogenes.

Answer 30

M, T, or R proteins

Question 31

Which Streptococci can grow in bile?

Answer 31

Streptococcus viridans and the Enterococcus bacteria (which, until recently, were considered Group D Streptococci)

Question 32

Which group A Streptococcal toxin is thought to play a role in acute rheumatic fever?

Answer 32

Streptolysin O

Question 33

What clinical sign is suggestive of Streptococcal pharyngitis?

Answer 33

Red dots on the pharynx

Question 34

What symptoms are more associated with viral infections?

Answer 34

Cough, runny nose, and age younger than 3 years

Question 35

Which spots (to swab) are the most likely to produce positive rapid antigen tests in a person with Strep throat?

Answer 35

The tonsils and posterior wall of the pharynx

Question 36

Positive rapid antigen tests will have ___________.

Answer 36

blue lines

Question 37

Which autoimmune Streptococcal illness is more likely to present in the summer?

Answer 37

PSGN

“You get Coca-Cola-colored urine in the season when you drink Coca Cola.”

Question 38

What are the symptoms of toxic shock?

Answer 38

DIC
Liver failure
Renal failure
ARDS
Scarlet fever rash

Question 39

Which bacterium has been implicated in perianal and perineal skin infections?

Answer 39

Group A Strep (Group Anus Strep

Question 40

True or false: Enterococci are susceptible to 3rd and 4th-generation cephalosporins.

Answer 40

False. Almost all Enterococci are resistant to penicillins, cephalosporins, Bactrim, clindamycin, and aminoglycosides. They can be treated with linezolid or tigecycline.