Gram Positive Cocci and Infective endocarditis

Question 1

beta hemolytic strep

Answer 1

• group A: pyogenes

- group B: agalactiae

Question 2

alpha hemolytic strep

Answer 2

• S. pneumoniae

- viridians strep

Question 3

gamma hemolytic strep

Answer 3

• enterococcus

Question 4

s. pyogenes leading cause of

Answer 4

• pharyngitis (strep throat)

- cellulitis (skin and soft tissue)

Question 5

post-streptoccal sequelae of s. pyogenes

Answer 5

• rheumatic fever and subsequent infective endocarditis

Question 6

acute rheumatic fever occurs when

Answer 6

• 2-3 weeks after untreated of inadequately treated strep throat

Question 7

what valves does acute rheumatic fever affect

Answer 7

• mitral/aortic

Question 8

what antibody titers are used in acute rheumatic fever diagnosis

Answer 8

• anti-streptolysin O

Question 9

important anti-phagocytic protein in S. pyogenes

Answer 9

• M protein

Question 10

how molecular mimicry of M proteins work

Answer 10

• antibodies bind host antigens and activate immune cells in tissues
• results in inflammation causing tissue damage

Question 11

gram positive organisms that cause infective endocarditis

Answer 11

• viridian’s streptococci
• staphylococci
• enterococci

Question 12

gram negative organism that cause infective endocarditis

Answer 12

• Haemophilus
• Actinobacillus
• Cardiobacterium
• Eikenella
• Kingella
• bartonella

Question 13

organisms that most affect native valve infective endocarditis (community acquired)

Answer 13

• S. aureus

- viridans

Question 14

organisms that most affect prosthetic valve infective endocarditis

Answer 14

• S. aureus

- coagulase negative staph

Question 15

organisms that most affect native valve infective endocarditis (nosocomial)

and also IV drug users and those with uncontrolled diabetes

Answer 15

• S. aureus

Question 16

S. aureus and S. pyogenes are found where in the body

Answer 16

• skin

Question 17

viridian’s streptococci are found where in the body

Answer 17

• oral cavity

Question 18

enterococci are found where in the body

Answer 18

• GI tract

Question 19

pathogenesis of infective endocarditis

Answer 19

• adherence to injured or inflamed valve surface
• persistence of bacteria
• proliferation
• dissemination

Question 20

between s. viridans and s. aureus, which has the higher virulence

Answer 20

• s. aureus

Question 21

between s. viridans and s. aureus, which can affect normal valves versus previously damaged heart valves

Answer 21

• S. viridans - requires previously damaged valves

- S. aureus - can affect previously normal valves

Question 22

between s. viridans and s. aureus, which causes subacute endocarditis with slow progression

Answer 22

• S. viridans

Question 23

between s. viridans and s. aureus, which cause acute bacterial endocarditis with rapid onset of fever or sepsis

Answer 23

• S. aureus

Question 24

pili (fimbriae) are expressed by

Answer 24

• both gram-negative and gram-positive pathogens

Question 25

which has hyaluronic acid

Answer 25

• group A strep

Question 26

which has polysaccharide

Answer 26

• S. aureus

Question 27

role of protein A

Answer 27

• avoids antibody-mediated opsonophagocytosis

- grabs the antibody by it’s Fc portion so it can’t signal to phagocytes

Question 28

what stimulates massive polyclonal expansion of T cells resulting in cytokine storm

Answer 28

• superantigen

Question 29

S. aureus superantigen causes

Answer 29

• toxic shock syndrome

- food poisoning

Question 30

S. pyogenes superantigen causes

Answer 30

• scarlet fever

Question 31

relative to streptococci _____ are intrinsically resistant to commonly used antibacterials

Answer 31

• enterococci

Question 32

most bacteria causing infective endocarditis are _______ (description of their oxygen requirement

Answer 32

• facultative anaerobes