Exam 5—COVID and Staphylococcus

Question 1

SARS & MERS mortality

Answer 1

10%
35%

Question 2

— COVID protein binds ——-

Answer 2

S1
ACE-2 receptor

Question 3

first covid gene translated

Answer 3

replicase

Question 4

negative strand copy of ssRNA is used to make…

Answer 4

(1) more positive strand copies
(2) small RNAs for spike + membrane + envelope + nucleocapsid proteins (S + M + E + N)

Question 5

2 cytokine related COVID syndromes

Answer 5

cytokine storm (IL6)
cytokine release syndrome

Question 6

cytokine release syndrom sx

Answer 6

fever and organ dysfunction - may have hemoptysis, renal failure, diarrhea

Question 7

Lopinavir, ritonavir, molnupiravir, paxlovid

Answer 7

covid protease inhibitors

Question 8

Hydroxychloroquine, ivermectin

Answer 8

no value

Question 9

Alpha-interferon

Answer 9

covid viral inhibitor

Question 10

remdesivir

Answer 10

inhibits covid RNA polymerases

Question 11

Regeneron, strovimab

Answer 11

covid monoclonal antibody against spikes

Question 12

Tolicizumab

Answer 12

covid monoclonal antibody against IL-6 receptor

Question 13

dexamethasone

Answer 13

steroid to reduce covid inflammation

Question 14

covid surface disinfectants

Answer 14

Metal surfaces antimicrobial (especially copper)
2% bleach
70% ethanol/rubbing alcohol
0.5% H2O2

Question 15

staph are Cat —

Answer 15

Pos

Question 16

coag-pos staph (5)

Answer 16

S. aureus
S. hyicus
S. intermedius
S. pseudintermedius
S. lutrae

Question 17

purpose of coagulase

Answer 17

Blood clots protect organisms from phagocytosis, antibody binding, and complement activation

Question 18

core genome

Answer 18

genome shared by 80-90% of species

Question 19

paragenome

Answer 19

complete set of genes found in species; core genome + strain specific genes

Question 20

MSCRAMM

Answer 20

microbial surface components recognizing adhesive factors

Question 21

MSCRAMM tropisms (5)

Answer 21

fibronectin binding, collagen binding, laminin binding, vibronectin binding, elastin binding

Question 22

clumping factor function

Answer 22

binds fibrinogen, causing clumps of plasma
also binds factor I, which degrades C3Bb

Question 23

abscess progression

Answer 23

Microbe associated molecular patterns (MAMPs) elicit cytokine response via TLRs
Coagulase builds a “cage” around the infection, creating a hard local infection
Toxin expression occurs

Question 24

tst gene

Answer 24

TSST-1

Question 25

TSST-1

Answer 25

Causes nonspecific T-cell activation, which causes release of large amounts of IL-1 and TNF-𝛼

Question 26

sx of TSS

Answer 26

fever, hypotension, n/v/d; multiple organs involved

Question 27

TSS mortality

Answer 27

65%

Question 28

responsible for food poisoning

Answer 28

staphylococcal enterotoxins (SEA and SEB)

Question 29

entA and entB

Answer 29

SEA and SEB

Question 30

enterotoxins made by ----% of S. aureus

Answer 30

30-50%

Question 31

Exfoliative toxin (Ets)

Answer 31

cleaves desmoglein-1 which is a cadherin that holds keratinized skin layer to basal layer of epidermis scalded skin syndrome

Question 32

bullous impetigo

Answer 32

Ets toxin (scalded skin)

Question 33

Panton-Valentine Leukocidin LukF and LukS

Answer 33

polymerize and form pores in membranes of WBCs

Question 34

Staphylokinase (Sak)

Answer 34

binds plasminogen and activates it to cleave fibrin in an uncontrolled way Bacteria are allowed to escape clot and spread to blood stream

Question 35

Sak causes circumvention of...

Answer 35

Regulation by PAI-1 and antiplasmin

Question 36

Staphylococcal alpha toxin Hla

Answer 36

Integrates into membranes of host cells, causing pores Causes alpha hemolysis

Question 37

MSCRAMM attachment C-terminus has a conserved ------- amino sequence this binds to the -------, which then passes it off to amide of one of the -------- this forms a peptide bond between the (above) and the MSCRAMM

Answer 37

LPXTG sortase glycine

Question 38

housekeeping sortase

Answer 38

sortase A

Question 39

iron acquisition sortase

Answer 39

sortase B

Question 40

pilus sortase

Answer 40

sortase C

Question 41

spore formation sortase

Answer 41

sortase D

Question 42

Fibronectin-binding protein (FnBP) species

Answer 42

Covering bacterial cell with fibronectin makes it “look” like the host S. aureus

Question 43

Protein A

Answer 43

Binds Fc of IgG, preventing opsonization Can also bind Fc of membrane-bound antibody, like IgD or IgM, which triggers apoptosis in the B-cell

Question 44

alternative lactamase used in some staph, which usually have no such activity

Answer 44

BlaZ lactamase

Question 45

main virulence mechanism of S. epidermidis

Answer 45

biofilms

Question 46

opportunity for S. epidermidis to infect

Answer 46

Catheters, prosthetics, pacemakers, microscopic tears in surgical gloves

Question 47

S. epidermidis capsule production of ------- leads evasion of immune system action

Answer 47

poly-γ-glutamic acid Protects from osmotic stress Contributes to biofilm formation Blocks phagocyte action Prevents action of antimicrobial peptides Combines with liberated DNA to form biofilm

Question 48

Phenol-soluble modulins (PSMs) δ-toxin species, action

Answer 48

Made by S. aureus, S. epidermidis, S. haemolyticus Cause inflammation Detergent like action disrupts cell membranes Can allow for phagosome escape

Question 49

only produces phenol-soluble toxins

Answer 49

S. epidermidis