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Infectious Diseases (CM) > Cyclic Peptide Antibiotics Med Chem > Flashcards

Cyclic Peptide Antibiotics Med Chem Flashcards

1
Q

Linear peptides are degraded____ and cyclic peptides are degraded ____.

A. Slower, Faster

B. Faster, Slower

A

B

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2
Q

T/F Human peptidases are able to recognize L-amino acids and degrade them but not D-amino acids found in cyclic peptide antibiotics

A

T

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3
Q

How do cyclic peptides evade degredation by human peptidases and last longer in the body?

A. Cyclic peptides contain L-amino acids and cannot be degraded by human peptidases

B. Cyclic peptides contain D-amino acids and cannot be degraded by human paptidases

C. Cyclic peptides have large cyclic structures that prevent them from fitting properly into the human peptidase enzymes

D. Cyclic peptides are linear in nature and are unable to be metabolized by most human peptidases

A

B

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4
Q

In the structure of vancomycin, the two circled groups are _____ and are linked by a ____ bond.

A. Sugars, Glycosidic

B. Amino Acids, Glycosidic

C. Sugars, Ester

D. Amino Acids, Ester

A

A

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5
Q

In the structure of vancomycin two groups are circled. The red group is a ____ molecule and the blue group is a ____ molecule.

A. Glucose, Vancosamine

B. Vancosamine, Glucose

A

B

Vancosamine is a glucose just like the structure circled in blue. The only difference is the amine group present in the structure.

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6
Q

Vancomycin is known as a ____ antibiotic.

A. Peptide

B. Glucose

C. Glycopeptide

D. Aglycopeptide

A

C

The top portion of vancomycin has a sugar moeity and the bottom cyclic portion consists of peptides

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7
Q

In the structure of vancomycin the green boxed structure is known as the ____ moeity.

A. Peptide

B. Glucose

C. Vancosamine

D. Aglycon

A

D

Vancomycin consists of a sugar (glucose) and a non-sugar moeity. The non-sugar moeity is called Aglycon. So remember:

Aglycon: Meaning the non-sugar moeity.

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8
Q

What is the MOA of vancomycin? (select all)

A. Binds to D-Ala-D-Ala murein monomer unit and inhibits Transglycosylase

B. Binds to peptidoglycan layer and creates a pore that allows extracellular content to degrade the bacteria

C. Binds to L-Ala-L-Ala murein monomer unit and inhibits Transglycosylase

D. Binds to 30s ribosomal subunits and inhibits protein synthesis

E. Inhibits transpeptidase (PBP) function

A

A, E

However, inhibition of transglycosylase is the primary mechanism of action. The transpeptidase is not. In a select all question you will choose both but if it is not a select all quesiton choose only the transglycosylase

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9
Q

What is the function of transglycosylase in bacteria?

A. No particular function

B. Causes the cross-linking of the NAM-NAG subunits

C. Adds newly-synthesized NAM-NAG monomers to the existing NAM-NAG polymer

D. Efflux antibiotics and render them ineffective

A

C

Transglycosylase will add new NAM-NAG monomers (+) to the existing polymer and extend the cell wall (<–)

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10
Q

What is the antibacterial spectrum of Vancomycin?

A. Gram Positive only

B. Gram Negative only

C. Both Gram Negative and Gram Positive

A

A

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11
Q

How is Vancomycin typically administered?

A. IV

B. Oral

C. SubQ

D. IM

A

A

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12
Q

Vancomycin is typically given IV due to poor oral absorption. For what reason would it be given orally?

A. Treatment of Herpes

B. GI infections such as Clostridium difficile

C. Treatment of Esophageal bacteria

D. Vancomycin is never given orally

A

B

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13
Q

What are the side effects of vancomycin?

A. Anaphylactoid reaction

B. Ototoxicity and Nephrotoxicity

C. Red-Man syndrome

D. All of the above

A

D

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14
Q

Red Man syndrome is reaction that causes the reddening of the skin (histamine release) and is a possible side effect of Vancomycin. What methods can be taken to reduce tha chances of this occuring? (Select All)

A. Rapid infusion

B. Slow infusion

C. Pretreat patient with corticosteroid

D. Pretreat patient with antihistamine

A

B, D

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15
Q

What type of bacteria will show resistance to vancomycin?

A. VRE bacteria

B. MRSA

C. MSSA

D. No reported bacterial resistance for vancomycin

A

A. VRE

VRE= Vancomycin Resistant Enterococcus

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16
Q

What is the bacterial resistance mechanism of Vancomycin Resistant Enterococcus (VRE)? (Select All)

A. Altered target site of D-Ala-D-Ala to D-Ala-D-Lactate

B. Increased production of Beta-Lactamases

C. Altered target site of D-Ala-D-Ala to D-Ala-D-Ser

D. Transfer of VanA gene to MRSA, creating VRSA

E. VISA- causing cell wall thickening of the bacteria

A

A, C, D, E

If D-Ala-D-Ala gets converted to Lactate or Serine it will alter the site vancomycin binds to and make it unable to bind

VRE can sometimes transfer the Van-A gene from itself to a MRSA bacteria and convert it to a VRSA (Vancomycin-Resistant Staphylococcus Aureus) bacteria that will not be resistant to methacillin and vancomycin

VISA causes the cell wall to thicken and does not allow vancomycin to bind properly

17
Q

In the picture provided Daptomycin has a circled group. What is the function of this particular group?

A. It is a phospholipid portion of Daptomycin that inserts itself into the cell membrane of bacteria, causing depolarization.

B. Binds to the cell wall and lyses the crosslinking of the peptidoglycan layer, destabilizing the bacteria.

C. Inhibits the synthesis of protein by binding to the 50s subunits

D. The phospholipid portion is only meant to increase the lipophilicity of the molecule

A

A

18
Q

What is the antibacterial spectrum of Daptomycin?

A. Gram Negative

B. Gram Positive

C. Both Gram Negative and Gram Positive

A

B

19
Q

All of the following statements about Daptomycin are true EXCEPT:

A. ADR of Muscle Pain/Weakness

B. Increased risk of Rhabdomyolysis with Statins

C. Bacterial resistance is due to bacterial cell wall thickening and charged repulsion due to phosphate.

D. Typically not used for MRSA or VRE infections.

A

D

The phosphate repulsion will prevent the daptomycin from being able to come in contact with the cell membrane.

20
Q

What is the purpose of the Diaminobutyric acid (DAB) in the structure of Colistin?

A. Inserts itself into the peptidoglycan layer of the bacteria and causes depolarization.

B. Becomes a positively charged (cationic) group that allows it to bind to the anionic Lipopolysaccharide layer and disrupt membrane integrity.

C. Gives it the ability to interact primarily with gram positive bacteria and lyse the cell membrane

D. The DAB group serves no particular function

A

B

The amino groups on DAB will become cationic (charged) at physiological pH and can bind to the LPS layer of gram negative bacteria and destabilize the membrane

21
Q

What is the bacterial spectrum of Colistin?

A. Gram Positive

B. Gram Negative

C. Both Gram Positive and Gram Negative

A

B

Remember it binds to the Lipopolysaccharide layer of bacteria and only gram negative bacteria contain an LPS layer.

22
Q

Which of the following statements is true regarding Colisin? (Select All)

A. Associated with nephrotoxicity

B. Can increase the neuromuscular blockade if given with paralytic agents such as Vecuronium or Atracurium

C. Increased chances of nephrotoxicity when given with other antibiotics such as Aminoglycosides, Amphotericin B and Vancomycin

D. Much higher GI discomfort

E. Hepatotoxicity

A

A, B, C

23
Q

T/F The mechanisms of bacterial resistance to Colisin include changes in the Lipopolysaccharide layer, decreased phosphate contents of the bacteria and lack of porins on the cell surface

A

F

Porins are irrelevant in the function of this particular drug due to its function at the LPS layer. Changes to the LPS layer and decreased phosphate contents are true though.

24
Q

What is the MOA of Bacitracin?

A. Binds to the LPS layer and causes its destabilization

B. Directly inhibits transpeptidase (PBP)

C. Interferes with dephosphorylation of the Phospholipid Carrier in bacterial cell-wall synthesis (Bactoprenol)

D. None of the above

A

C

Bactoprenol is responsible for bringing new NAM-NAG monomers to the bacterial cell surface to construct the peptidoglycan layer. However, in order to do that it must first be dephosphorylated but Bacitracin inhibits the dephosphorylation of bactoprenol so it cannot build the cell wall.

25
Q

What is the antibacterial spectrum of Bacitracin?

A. Gram Positive

B. Gram Negative

C. Both Gram Positive and Gram Negative

A

A

26
Q

What are the side effects of Bacitracin?

A. Nephrotoxicity

B. Neurotoxicity

C. Bone-Marrow toxicity

D. All of the above

A

D

27
Q

Bacitracin has major side effects such as Neurotoxicity, Nephrotoxicity and Bone-Marrow toxicity. Because of these ADRs it is typically given____.

A. Orally

B. IV

C. IM

D. Topically

A

D

28
Q

T/F Bacitracin requires a metal ion in order to exhibit its activity and is therefore known as a metalo-antibiotic

A

T

29
Q

Mupirocin is a ____ antibiotic

A. Lipid

B. Cyclic-peptide

C. Metaloantibiotic

A

A

As you can see in it’s structure it does not have the numerous cyclic structures that the other cyclic peptide antibiotics contain. Rather, it has a large carbon chain on the right side of the molecule.

30
Q
A

Infectious Diseases (CM) (10 decks)

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