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Flashcards in ID 4 Deck (50):
1

c perfringens toxin

alpha toxin

2

alpha toxin mechanism

phospholipase (lecithinase) that degrades tissue and cell membranes

3

Alpha toxin manifestation on agar

hemolytic "double zone" of hemolysis on blood agar

4

what does alpha toxin lead to?

myonecrosis ("gas gangrene")

5

strep pyogenes toxin?

streptolysin O

6

streptolysin O MOA

protein that degrades cell membrane, thus lysing RBCs

7

what do you use to diagnose ARF?

antistreptolysin o antibodies (ASO)

8

staph aureus toxin?

Toxic shock syndrome toxin (TSST-1)

9

strep pyogenes toxin?

Exotoxin A

10

TSST-1/exotoxin A MOA?

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

11

staph aureus toxin causing scalded skin syndrome?

exfoliative toxin

12

staph aureus toxin causing food poisoning?

enterotoxin

13

LPS components

O antigen + core polysaccharide + lipid A

14

How is endotoxin released?

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

15

main effects of endotoxin

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

16

what other cytokine contributes to fever?

TNF-alpha

17

Macrophage cytokines causing hypotension?

TNF-alpha + nitric oxide

18

endotoxin and DIC mechanism

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

19

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

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

20

food poisoning scenario for staph aureus and why

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

21

What is MRSA resistant to?

methicillin and *nafcillin because of altered penicillin-binding protein

22

Labs in staphylococcal toxic shock syndrome

1) increased AST + ALT
2) increased bilirubin

23

Differentiating staphylococcal toxic shock syndrome from streptococcus pyogenes TSS

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

24

S aureus food poisoning presentation

Non bloody diarrhea and emesis

25

Problem with s aureus food poisoning

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

26

What is a staph abscess?

staph forms a fibrin clot around it's itself.

27

saprophyticus appearance

cocci in clusters

28

Where is saprophyticus normally found?

Flora of female genital tract and perineum.

29

second most common cause of uncomplicated UTI in young women?

saprophyticus

30

Cause of sepsis in patients with sickle cell disease?

strep pneumo

31

virulence factor of strep pneumo?

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

32

sputum with strep pneumo?

"rusty"

33

viridans group streptococcus causing endocarditis

s sanguinis (sanguinis means blood)

34

how do viridans group adhere to valves?

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

35

scarlet fever toxin

erythrogenic toxin

36

How do you test for GBS

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

37

GBS prophylaxis?

intrapartum penicillin

38

streptococcus bovis structure

gram positive cocci

39

what is s gallolyticus?

S bovis biotype 1

40

enterococci?

E faecalis
E faecium
VRE

41

where are enterococci found?

normal colonic flora

42

enterococci characteristisc?

penicillin G resistant

43

VRE primary concern?

impt cause of nosocomial infection

44

enterococci cause...

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

45

enterococci testing...

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

46

enterococci structure

Gram positive cocci in chains

47

Unique thing about bacillus anthracis

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

48

cutaneous anthrax..

rarely progresses to bacteremia and death.

49

cutaneous anthrax description

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

50

pulmonary anthrax pathogenesis

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