Peptidoglycan Synthesis and Major Antibiotics Flashcards Preview

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Flashcards in Peptidoglycan Synthesis and Major Antibiotics Deck (60)
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1

Regarding case 4, the patient presents with sudden onset high fever. He'd had the flu over the last 3 days. What is the significance of the high fever? What is the significance of his blood pressure being recorded as 60/0?

High fever - bacterial cause
60/0 BP - TSS or similar antigen causing shock

2

What is a macular erythroderma? What is the significance of the patient's sore throat with cough?

Flat red rash
Staph or strep infection

3

What were the 3 likely diagnosis for the patient based on the presenting symptoms? Which ended up being correct?

Septic shock due to gram-positive or gram negative
bacteria
Staphylococcal toxic shock syndrome following
influenza *** (Correct)***
Streptococcal toxic shock syndrome

4

Why was the patient administered fluids and electrolytes? Why was ceftriaxone the first drug used despite not knowing the result of the throat cultures?

Fluids and electrolytes to stabilize blood pressure
Ceftriaxone provides broad coverage for gram positive and negative bacteria

5

Regarding case 4, what was the pathogenic organism? What was the new diagnosis? How was the pathogenic organism classified and what new drug was used to treat the patient?

Staph. aureus
S. Aureus necrotizing pneumonia
Community acquired MRSA
Vancomycin

6

What is the drug class that ceftriaxone belongs to? Why was it unable to treat the patients pathogen? What other drug class would have been similarly unsuccessful?

Cephalosporin
Because Cephalosporins can't treat MRSA
Penicillins

7

What was the specific strain of MRSA in case 4? What is the virulence factor associated with this strain?

CA MRSA USA400 strain
High levels of superantigen (enterotoxin C)

8

Based on the case, what were the 2 mistakes made regarding the patient's treatment?

Not using vancomycin immediately
Not using IVIG to neutralize the superantigen

9

What is the downside of vancomycin overuse? What is the downside of IVIG treatment?

Increase chance of resistance
IVIG is expensive

10

What is the function of the peptidoglycan layer? What are the 2 types of linkages found in the peptidoglycan wall? What happens if the bacteria don't have their peptidoglycan walls?

Provide strength and rigidity to bacterial cells
Glycosidic and peptide linkages
Bacteria lyse due to turgor pressure

11

When does peptidoglycan synthesis occur? What types of cells have peptidoglycans?

During cell division (binary fission)
Only bacterial cells

12

Differentiating between gram negative and positives, which will have peptidoglycan that is partially covalently bound to lipoproteins?

Gram negative - partially covalently bound insinuates decreased cross linking, a property of gram negative cell wall

13

Differentiating between gram negative and positives, who has thinner peptidoglycan layers? Where are the gram negative peptidoglycan layer found?

Thinner in gram negative
Found in the periplasm

14

What are gram positive peptidoglycans linked to (3)? Are they more or less crosslinked than gram negatives?

Techoic acids, proteins and to itself
More (75% vs. 25%)

15

What are the 2 major components of peptidoglycan? What is the type of bond that links these components?

N-acetyl muramic acid and N-acetylglucosamine
Beta-1,4, glycosidic bonds

16

What is the difference between N-acetyl muramic acid and N-acetylglucosamine?

N-acetylglucosamine plus a lactyl on carbon 3 forms N-acetyl muramc acid

17

N-acetyl muramic acid and N-acetylglucosamine; which has a tetrapeptide with alternating L- and D-amino acids through the lactyl groups? How are these tetrapeptides linked to each other? In other words, which moiety works to bind adjacent chains?

N-acetyl muramic acid
Peptide bonds

18

What is special about the D-amino acids found on the tetrapeptide in N-acetyl muramic acid?

Found only in bacteria

19

The tetrapeptide associated with N-acetyl muramic acid is L-alanyl-D-glutamyl-L-amino acid-D-alanine. What is the significance of the 3 residue? What is it usually?

Varies with bacterial species
Usually lysine or a diaminopimelic acid

20

What is the residue that is often involved with crosslinking within the peptidoglycan?

A glycine, but varies with species

21

What is another name for phosphonomycin? What step in peptidoglycan synthesis does it block? What is the mechanism?

Fosfomycin
Blocks the conversion of UDP-NAG to UDP-NAM
It is a phosphoenonol pyruvate analogue, a molecule necessary for that conversion

22

At what step in peptidoglycan synthesis does D-cycloserine work? What is the mechanism? What disease it is specifically used to treat?

It prevents the addition of D-alanine as a dipeptide to the UDP-NAP-(3AA) molecule
Blocks the enzymes responsible for those steps by acting as an analogue of L-Ala
Tuberculosis

23

In what cellular compartment do phosphonomycin and D-cycloserine work?

In the cytoplasm

24

To transition from the cytosol to the cell membrane in peptidoglycan synthesis, UDP-NAM-(Pentapeptide) becomes _. What is the cell wall precursor?

BPP-NAM-(peptapeptide)
BPP-NAM - (NAG)-(peptapeptide)

25

What is the mechanism by which bacitracin works? What is BP? BPP? What is its function?

It prevents the conversion of BPP to BP. BPP is a required component of the cell wall precursor
BP - undecaprenol phosphate
BPP - Undecaprenol pyrophosphate (2 phosphates)
It is a lipid carrier

26

What is a specific example of a pathogenic microbe that is sensitive to bacitracin?

Group A strep

27

In what cellular compartment does bacitracin work?

It works in the inner cell membrane

28

In what cellular compartment does vancomycin, penicillin an dthe cephalosporins work?

The work in the exterior of the cell or in the periplasm

29

What is the mechanism by which vancomycin works?

It binds the 2 D-ala molecules, preventing the cross brigding to the existing cell wall

30

What is the mechanism by which the penicillins and cephalosporins work? As a group, penicillins and cephalosporins are known as _

The bind penicillin binding proteins, thereby blocking the transpeptidation reaction
Beta lactams