Streptococci

Question 1

s. pyogenes M protein functions

Answer 1

• binds to keratinocytes

- prevents opsonization by complement (binds fibrinogen and binds complement control protein)

Question 2

s. pyogenes hyaluronic acid capsule purpose

Answer 2

antiphagocytic structure that serves as camoflage to the immune system

Question 3

hyaluronidase secreted by bacteria can ____ the capsule, and also allows s. pyogenes _____

Answer 3

digest; to spread through tissue

Question 4

streptokinase binds _____- enzymatic conversion to ____

Answer 4

plasminogen; plasmin

Question 5

plasmin coated GAS can degrade and spread through _____ resulting in invasive disease

Answer 5

fibrin (blood clots)

Question 6

_____ has therapeutic use in treating _____

Answer 6

streptokinase; blood clots

Question 7

_____ cause rash associated with scarlet fever (toxin spreads through blood)

Answer 7

erythrogenic toxins or streptococcal pyrogenic exotoxins (SpeA, SpeB, and SpeC)

Question 8

____ is the most abundant extracellular protein

Answer 8

SpeB

Question 9

SpeA and SpeC are bacterial _____ that non-specifically activate a large subset of ____

Answer 9

superantigens; T-cells

Question 10

SpeA and SpeC cause ____

Answer 10

streptococcal toxic shock sundrome (STSS)

Question 11

most common manifestations of GAS

Answer 11

• acute pharyngitis (strep throat)

- pyoderma- GAS infection of the skin- impetigo

Question 12

suppurative (pus) infections of s. pyogenes GAS

Answer 12

upper respiratory tract:
acute pharyngitis (strep throat)
scarlet fever (toxigenic strains)

Question 13

tx for suppurative infections

Answer 13

10 days penicillin

Question 14

skin infections caused by GAS (also suppurative)

Answer 14

1. cellulitis
2. erysipelas
3. impetigo

Question 15

tx for skin infections:

Answer 15

topical antibiotics: mupirocin ointment, oral antibiotics if widespread infection

Question 16

non-suppurative infections (autoimmune diseases) caused by GAS

Answer 16

• acute rheumatic fever (ARF)

- acute poststreptococcal glomerulonephritis (APSGN)

Question 17

ARF only follows _____

Answer 17

pharyngeal infections by rheumatogenic strains

Question 18

APSGN only follows ____

Answer 18

pharyngeal or skin infections by nephritogenic strains

Question 19

Symptoms of ARF

Answer 19

• fever
• painful joints (arthritis)
• chorea (fidgity or abnormal movements)
• heart murmur
• non itchy erythema marginatum rash

Question 20

symptoms of APSGN

Answer 20

• edema
• gross hematuria (tea colored urine)
• hypertension

Question 21

tx for APSGN:

Answer 21

sodium reduction
diuretics
95% recover

Question 22

group B streptococci, particularly s. agalactiae (aerobic) is the leading cause of _____

Answer 22

neonatal sepsis and meningitis

Question 23

Group B streptococci have _____ that prevents opsonization and phagocytosis

Answer 23

polysaccharide capsule

Question 24

____ streptococci also have hyaluronic acid capsule, similar to group A

Answer 24

Group C

Question 25

groups C and D streptococci are implicated in ____ but not _____

Answer 25

APSGN; ARF

Question 26

enterococci cause:

Answer 26

nosocomial infections, urinary tract infections, and endocarditis

Question 27

non-enterococcal group D streptococci

Answer 27

s. bovis- most common for human disease (from cows, sheep, other ruminants)
s. suis- pigs to humans

Question 28

viridans (greening) streptococci is ____ strep

Answer 28

alpha-hemolytic

Question 29

viridans most common cause of _____

Answer 29

subacute bacterial endocarditis