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Phar 506 > Antibiotics: Cell wall biosynthesis and its inhibitors > Flashcards

Antibiotics: Cell wall biosynthesis and its inhibitors Flashcards

1
Q

T/F: Enzymes of cells biosynthesis are unique to bacteria and are good targets for antibiotics

A

True

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2
Q

T/F: Gram negative have a thick peptidoglycan wall

A

False: Gram positive have a thick peptidoglycan wall

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3
Q

What is the building block for producing peptidoglycans in Gram positive bacteria, what is it made from

A

Lipid II/ N-acetyl glucosamine (NAG), N-acetyl muramic acid (NAM), Stem (penta) peptide

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4
Q

What is the most important amino acid in peptidoglycan

A

Alanine

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5
Q

T/F: Peptidoglycan sugars cross link to create polysacchride chains

A

False: Peptidoglycan peptide tails cross link with each other to create polysacchride chains through creating peptide bridges

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6
Q

What does transpeptidase do

A

Catalyzes crosslinkages in peptidoglycans

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7
Q

What is a B-lactam group

A

four membered cyclic amide

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8
Q

What are the drug classes that use Beta lactam grous

A

penicillin, cephalosporins, carbapenenms and monobactams

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9
Q

What is the mechanism of action for Beta-lactam antibiotics

A

TPase misidentifies Beta-lactam strucutre as D-Ala-D-Ala bond and then binds covalently making it irreversibly inactive

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10
Q

What is a structural difference of Penicllin G, what does it work best against, how is it administered

A

Beta-lactam ring fused to a thiazolidine ring, gram-positive bacteria, IM or IV

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11
Q

What is the precursor for many different manufactured Beta-lactam antibiotics

A

6-aminopenicillanic acid (6-APA)

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12
Q

What were changes to Beta-lactam antibiotics that allowed them to become orally available, what are they

A

Electron withdrawing side chains decrease the rate of acid hydrolysis/ amoxicillin and cloxacillin

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13
Q

What were penicllin improvements that allowed attack of gram negative bacteria/ what are examples of this

A

Slight polar side chains allowed entry through porins (-NH2 or COOH)/ Ampicillin, Amoxacillin, Carbenicllin

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14
Q

What are Beta-lactamases

A

Enzymes that hydrolyze amide bond in Beta-lactam rings

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15
Q

What are improvements in penicllin that allows resistance to Beta-lactamases, what are examples

A

Bulky side chains hinder access/ Methicillin and Cloxacillin

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16
Q

What is the MOA of Beta-lactamase inhibitors/ what are some examples

A

posses a Beta lactam ring and inactivate the enzyme without being degraded/ clavulanic acid, sulbactam, tazobactam

17
Q

What is a starting compound for semisynthetic cephalosporins

A

7-aminocephalosporanic acid (7-ACA)

18
Q

T/F: The first generations of cephalosporins are mostly active agains gram positive coccie and streptococci

A

True

19
Q

T/F: Third generation cephalosporins have good activity against gram positive and gram negative pathogens

A

False: Third generation cephalosporins have better activity for gram-negatives and somewhat reduced activity against gram-positive pathogens

20
Q

What does the cephalosporin moxalactam do in order to resist Beta-lactamases

A

Bulky side chains

21
Q

T/F: Carbapenems are only good against Gram-positive

A

False: Carbapenems have good activity against gram positive and gram negative bacteria

22
Q

T/F: Carbapenems are only used IV

A

True

23
Q

What are other types of cell wall inhibitors that are not Beta-lactams

A

Fosfomycin, Bacitracin, Vancomycin

24
Q

What is the MOA of bacitracin, why is it only for external barriers

A

Interfers with dephosphorylation of the lipid carrier that moves the peptidoglycan presursors across the cytoplamic membrane, also interferes with mammalian cells

25
Q

T/F: Vancomycin is a glycopeptide and is active against gram positive bacteria

A

True

26
Q

What is the MOA of vancomycin

A

Binds D-Ala -D-Ala residues at the end of the peptioglycan precursor lipid II, therefore not allowing Transpeptidase to catalyze cross linking of strands

27
Q

What is improved version of Vancomycin, how is it improved

A

Televancin, has an additional hydrophobic side chain and a polar phosphate group binding the cell membrane and increasing the membrane permeability

28
Q

What gene causes vancomycin resistance, what change does it cause

A

VRSA, replaces D-Ala-D-Ala for D-Ala-D-Lactate

29
Q

T/F: Vancomycin can be used in treatment of infections that are methicllin and cephalosporin resistant

A

True

30
Q

T/F: Monobactams (Aztreonam/Azactam) was developed as narrow-spectrum antibiotic targeting aerobic gram-negative bactera. It can be used in those allergic to Penicillin

A

True

Phar 506 (37 decks)

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