ID 4

Question 1

c perfringens toxin

Answer 1

alpha toxin

Question 2

alpha toxin mechanism

Answer 2

phospholipase (lecithinase) that degrades tissue and cell membranes

Question 3

Alpha toxin manifestation on agar

Answer 3

hemolytic “double zone” of hemolysis on blood agar

Question 4

what does alpha toxin lead to?

Answer 4

myonecrosis (“gas gangrene”)

Question 5

strep pyogenes toxin?

Answer 5

streptolysin O

Question 6

streptolysin O MOA

Answer 6

protein that degrades cell membrane, thus lysing RBCs

Question 7

what do you use to diagnose ARF?

Answer 7

antistreptolysin o antibodies (ASO)

Question 8

staph aureus toxin?

Answer 8

Toxic shock syndrome toxin (TSST-1)

Question 9

strep pyogenes toxin?

Answer 9

Exotoxin A

Question 10

TSST-1/exotoxin A MOA?

Answer 10

Bind to MHC II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN gamma, and TNF-alpha –> shock

Question 11

staph aureus toxin causing scalded skin syndrome?

Answer 11

exfoliative toxin

Question 12

staph aureus toxin causing food poisoning?

Answer 12

enterotoxin

Question 13

LPS components

Answer 13

O antigen + core polysaccharide + lipid A

Question 14

How is endotoxin released?

Answer 14

Upon cell lysis or *by living cells by blebs detaching from outer surface membrane.

Question 15

main effects of endotoxin

Answer 15

1) macrophage activation (TLR4)
2) complement activation
3) tissue factor activation
* extremely heat stable

Question 16

what other cytokine contributes to fever?

Answer 16

TNF-alpha

Question 17

Macrophage cytokines causing hypotension?

Answer 17

TNF-alpha + nitric oxide

Question 18

endotoxin and DIC mechanism

Answer 18

endotoxin –> tissue factor activation –> coagulation cascade –> DIC

Question 19

how do you differentiate between alpha and beta-hemolysis on culture?

Answer 19

beta-hemolytic shows a clear area surrounding colony (see FA 119)

Question 20

food poisoning scenario for staph aureus and why

Answer 20

Rapid-onset food poisoning. It’s preformed toxin that has a short incubation period (2-6 hr)

Question 21

What is MRSA resistant to?

Answer 21

methicillin and *nafcillin because of altered penicillin-binding protein

Question 22

Labs in staphylococcal toxic shock syndrome

Answer 22

1) increased AST + ALT

2) increased bilirubin

Question 23

Differentiating staphylococcal toxic shock syndrome from streptococcus pyogenes TSS

Answer 23

1) staphylococcal presentation = fever + vomiting + rash + desquamation + shock + end-organ failure.
2) strep pyogenes toxic shock-like syndrome = painful skin infection

Question 24

S aureus food poisoning presentation

Answer 24

Non bloody diarrhea and emesis

Question 25

Problem with s aureus food poisoning

Answer 25

It's a heat stable enterotoxin that isn't destroyed by cooking.

Question 26

What is a staph abscess?

Answer 26

staph forms a fibrin clot around it's itself.

Question 27

saprophyticus appearance

Answer 27

cocci in clusters

Question 28

Where is saprophyticus normally found?

Answer 28

Flora of female genital tract and perineum.

Question 29

second most common cause of uncomplicated UTI in young women?

Answer 29

saprophyticus

Question 30

Cause of sepsis in patients with sickle cell disease?

Answer 30

strep pneumo

Question 31

virulence factor of strep pneumo?

Answer 31

Capsule. Without it's capsule, strep pneumo is not virulent.

Question 32

sputum with strep pneumo?

Answer 32

"rusty"

Question 33

viridans group streptococcus causing endocarditis

Answer 33

s sanguinis (sanguinis means blood)

Question 34

how do viridans group adhere to valves?

Answer 34

makes dextrans, which bind to fibrin-platelet aggregates on damaged heart valves.

Question 35

scarlet fever toxin

Answer 35

erythrogenic toxin

Question 36

How do you test for GBS

Answer 36

1) produces CAMP factor, which enlarges the area of hemolysis formed by S aureus (*NOT cAMP) 2) Hippurate test positive

Question 37

GBS prophylaxis?

Answer 37

intrapartum penicillin

Question 38

streptococcus bovis structure

Answer 38

gram positive cocci

Question 39

what is s gallolyticus?

Answer 39

S bovis biotype 1

Question 40

enterococci?

Answer 40

E faecalis E faecium VRE

Question 41

where are enterococci found?

Answer 41

normal colonic flora

Question 42

enterococci characteristisc?

Answer 42

penicillin G resistant

Question 43

VRE primary concern?

Answer 43

impt cause of nosocomial infection

Question 44

enterococci cause...

Answer 44

1) UTI 2) biliary tract infections 3) subacute endocarditis (*following GI/GU procedures)

Question 45

enterococci testing...

Answer 45

1) PYR positive 2) variable hemolysis 3) can grow in 6.5% NaCl 4) can grow in bile

Question 46

enterococci structure

Answer 46

Gram positive cocci in chains

Question 47

Unique thing about bacillus anthracis

Answer 47

Only bacterium with a polypeptide capsule (contains D-glutamate)

Question 48

cutaneous anthrax..

Answer 48

rarely progresses to bacteremia and death.

Question 49

cutaneous anthrax description

Answer 49

*painless papule surrounded by vesicles that leads to ulcer with black eschar (*painless, necrotic)

Question 50

pulmonary anthrax pathogenesis

Answer 50

inhalation of spores --> flu-like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis, and shock.