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iPTX III > Antibiotics Med Chem > Flashcards

Antibiotics Med Chem Flashcards

1
Q

5 main MOAs of antibiotics

A
  1. Inhibition of cell wall synthesis
  2. Disruption of cell membrane structure or function
  3. Inhibition of protein synthesis
  4. Inhibition of nucleic acid synthesis, structure or function
  5. Block metabolic reactions
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2
Q

MOA of penicillins

A

Inhibition of cell wall synthesis. Interferes with transpeptidation reaction that creates cross links in bacterial cell wall formation

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3
Q

Beta lactam structure

A

4 membered cyclic amide ring

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4
Q

Which abx classes are beta lactam?

A

. Penicillin
. Cephalosporins
. Monobactams
. Carbapenems
. Beta lactamase inhibitors

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5
Q

How many atoms in a beta-lactam ring?
* 3
* 4
* 5
* 6

A

4

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6
Q

How many rings in 6-Aminopenicillanic acid (the core structure of penicillin)?
* 1
* 2
* 3
* 4

A

2

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7
Q

Traditional penicillins largely exhibit their action on gram (positive/negative) bacteria

A

Positive
Also has some gram negative cocci coverage

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8
Q

Gram negative bacteria have a (hydrophilic/hydrophobic) outer membrane not present in gram positive bacteria

A

Hydrophobic

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9
Q

What is the target of penicillins as antibiotics
* lactamase
* transpeptidase
* beta-lactam
* 6-APA

A

transpeptidase

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10
Q

Penicillin has (bacteriostatic/ bactericidal) activity

A

Bactericidal

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11
Q

Limitations with penicillin G

A
  1. Sensitive to stomach acids (no PO)
  2. Sensitive to β-lactamases - enzymes which hydrolyze
    the β-lactam ring
  3. Limited range of activity
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12
Q

Penicillin V has better oral administration than penicillin G due to

A

additional oxygen atom in its structure. Better acid stability, however, sensitive to beta lactamases, slightly less active than penicillin G and allergy problems with some patients

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13
Q

What is not the limitation of penicillin G?
* Sensitive to stomach acid
* Sensitive to beta-lactamase
* Limited activity on Gram-negative
* Bactericidal

A

Bactericidal

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14
Q

What is the function of beta-lactamase inhibitors?
* Inhibit protein synthesis
* Inhibition of cell wall synthesis
* Disruption of cell membrane structure or function
* Improve the stability of penicillins

A

Improve the stability of penicillins

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15
Q

Which one is not an effective way to improve the properties of penicillins?
* Adding electronic-withdraw groups in the sidechain
* Using with clavulanic acid together
* Modifying sidechain (adding NH2, COOH or Urea groups)
* Removing carboxylic acid group connecting the thiazolidine ring

A

Removing carboxylic acid group connecting the thiazolidine ring

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16
Q

Cephalosporin and monobactam target/MOA

A

Targets transpeptidase to inhibit bacterial cell wall synthesis

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17
Q

Cephalosporins are relatively (stable/unstable) in acid and are highly (resistant/sensitive) to beta lactamase

A

Stable. Resistant.

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18
Q

What is the major difference between the core structure cephalosporins and penicillins
* The number of rings
* The size of rings
* One with sulfur and the other does not have sulfur
* hydrogen cis configuration

A

The size of rings

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19
Q

Which property increase from 1st generation to 4th generation
Cephalosporins
* Activity on Gram+ bacteria
* Activity on Gram- bacteria

A

Activity on Gram- bacteria

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20
Q

Difference in structure between penicillin and carbapenems

A

Replaced S with C in 5 membered ring

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21
Q

Difference in structure between penicillin and monobactams

A

Removal of second ring

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22
Q

Carbapenems have a (narrower/broader) spectrum of activity compared to cephalosporins and penicillins

A

Broader

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23
Q

True or false: Carbapenems are generally reserved for suspected multi-drug resistant organism in hospitalized patients

A

True

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24
Q

Why is imipenem often prepared in combination with cilastatin?

A

Imipenem is easily hydrolyzed by
dehydropetidase in the body. So the clinical
preparation is the mixture with peptidase inhibitor named cilastatin.

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25
Q

Monobactams cover most aerobic gram (positive/negative) bacteria

A

Negative

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26
Q

Vancomycin is similar to penicillin G EXCEPT
* Inhibition of cell wall synthesis
* They are both beta-lactam inhibitors
* administered intravenously
* selectively active against Gram+ bacteria

A

They are both beta-lactam inhibitors

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27
Q

What is the mechanism of action of Polymixin?
* Inhibit protein synthesis
* Inhibit folic acid synthesis
* Inhibition of cell wall synthesis
* Disruption of cell membrane structure or function
* Inhibition of nucleic acid synthesis, structure or function

A

Disruption of cell membrane structure or function

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28
Q

Protein synthesis central dogma

A

Transcription from DNA to mRNA then translation from mRNA to protein

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29
Q

Aminoglycosides MOA

A

Inhibit protein synthesis by binding to 30S ribosome causing misreading of mRNA

30
Q

True or false: Aminoglycosides have activity against gram negative bacteria and anaerobes

A

False. They have gram negative coverage, but no anaerobe coverage

31
Q

Why can’t aminoglycosides be administered orally?
* They are very hydrophobic
* They are very sensitive to stomach acid
* They are very sensitive to lactamase
* They are very polar molecules

A

They are very polar molecules

32
Q

Which compound acts as a 30s ribosome inhibitor in bacterial protein
synthesis?
* Penicillin G
* Vancomycin
* Carbapenem
* Gentamicin

A

Gentamicin

32
Q

Which of the following statements about aminoglycosides is FALSE?
A) include streptomycin
B) bind to the 30S ribosomal subunit of the bacterial ribosome
C) It is a broad spectrum antibiotics
D) It can cause ototoxicity

A

C) It is a broad spectrum antibiotics

33
Q

Which antibiotic is very effective against Gram-negative bacteria?
* Penicillin G
* Vancomycin
* Cephalothin (1st generation of Cephalosporins)
* Streptomycin

A

Streptomycin

34
Q

Which compound are not recommended to use with aminoglycoside?
* Penicillin G
* Vancomycin
* Cephalothin (1st generation of Cephalosporins)
* Streptomycin

A

Vancomycin

35
Q

Tetracyclines MOA

A

Inhibits protein synthesis

36
Q

Tetracyclines are (bacteriostatic/bactericidal)

A

Bacteriostatic

37
Q

Tetracycline adverse effects

A

.Staining/impairment of bone and teeth
.Aplastic anemia
.Gray baby syndrome
.Irreversible bone marrow damage
.Leukemia

38
Q

How many rings in doxycycline?
* 2.
* 3.
* 4.
* 5.

39
Q

Which one is a broad-spectrum antibiotics?
* Penicillin G
* Vancomycin
* Tetracycline
* Aminoglycoside

A

Tetracycline

40
Q

Which compound acts as a 30s ribosome inhibitor in bacterial protein synthesis?
* Penicillin G
* Vancomycin
* Doxycycline
* Cephalosporin

A

Doxycycline

41
Q

Which abx classes are 30s inhibitors?

A

.Aminoglycosides
.Tetracyclines

42
Q

Which abx classes are 50s inhibitors?

A

.Chloramphenicol
.Macrolides
.Clindamycin
.Oxazolidinones
.Pleuromutilins

43
Q

Which one is a broad-spectrum antibiotics?
* Penicillin G
* Vancomycin
* Chloramphenicol
* Aminoglycoside

A

Chloramphenicol

44
Q

Which one is NOT a broad-spectrum antibiotics?
* Tetracycline
* Carbapenems
* Chloramphenicol
* Monobactam

A

Monobactam

45
Q

What has the overuse of antibiotics led to?
A) Bacterial strains that are more susceptible to antibiotics.
B) Resistant strains of bacteria that are immune to antibiotics

A

B) Resistant strains of bacteria that are immune to antibiotics

46
Q

Which two antibiotics share the same binding site?
* Macrolides and clindamycin
* Tetracyclines and Macrolides
* Oxazolidinones and Tetracyclines
* Aminoglycosides and Chloramphenicol

A

Macrolides and clindamycin

47
Q

Which antibiotics is bactericidal?
* Tetracyclines
* Macrolides
* Clindamycin
* Aminoglycosides

A

Aminoglycosides

48
Q

____ are a common substitute against gram+ bacteria for patients with a penicillin
allergy.
* Macrolides
* Aminoglycoside
* Polymixin
* Monobactam

A

Macrolides

49
Q

Which of the following mechanisms can make a bacterium resistant to
antibiotics?
* A) chemical modification of the drug
* B) pumping the drug out of the cell
* C) enhancing the binding of the drug to the ribosome
* D) A and B
* E) A, B and C

A

D) A and B

50
Q

Which of the following antibiotics are totally synthetic?
A) Macrolides
B) Linezolid
C) Aminoglycosides
D) Streptomycin
E) Erythromycin

A

B) Linezolid

51
Q

Which of the following antibiotics bind to the 50S subunit of bacterial ribosomes
thereby inhibiting protein synthesis?
A) Aminoglycosides and Tetracyclines
B) Tetracyclines and Macrolides
C) Oxazolidinones and Tetracyclines
D) Aminoglycosides and Chloramphenicol
E) Oxazolidinones and Chloramphenicol

A

E) Oxazolidinones and Chloramphenicol

52
Q

Antibiotics that inhibit bacterial protein synthesis target the 80S ribosomes and
therefore do not affect eukaryotes which have 70S ribosomes.
A) True
B) False

53
Q

true or false: Bacteria cannot synthesize folic acid and must obtain it from outside sources

A

False. Bacteria can’t use folic acid obtained from their environment –
they have to synthesize it on their own

54
Q

Which one is a broad-spectrum antibiotics?
* Penicillin G
* Vancomycin
* Sulfa drugs
* Aminoglycoside

A
  • Sulfa drugs
55
Q

What is the mechanism of action of Sulfa drugs?
* Inhibit protein synthesis
* Inhibit folic acid synthesis
* Inhibition of cell wall synthesis
* Disruption of cell membrane structure or function
* Inhibition of nucleic acid synthesis, structure or function

A

Inhibit folic acid synthesis

56
Q

Sulfa drugs compete with ______ to inhibit bacterial folic acid synthesis
* 6-APA
* beta-lactam
* PABA
* tRNA

57
Q

Trimethoprim is ____ % bioavailable and has a half life of ____ hrs

A

100%. 10hrs

58
Q

True or false: Trimethoprim should not be used in combination with sulfa drugs because they both inhibit bacterial folic acid synthesis

A

False. They inhibit different steps in folic acid formation, having synergy in their action

59
Q

What is the target of trimethoprim?
* 30S ribosome
* Transpeptidase
* beta-lactamase
* dihydrofolate reductase

A

dihydrofolate reductase

60
Q

What is the mechanism of action of co-trimoxazole?
* Inhibit protein synthesis
* Inhibit folic acid synthesis
* Inhibition of cell wall synthesis
* Disruption of cell membrane structure or function
* Inhibition of nucleic acid synthesis, structure or function

A

Inhibit folic acid synthesis

61
Q

Co-trimoxazole is a combination of trimethoprim and ______?
* Aminoglycoside
* Penicillins
* Sulfa drugs
* Macrolides

A

Sulfa drugs

62
Q

What are the two primary processes of DNA synthesis?

A

Transcription and replication

63
Q

What is the target of quinolones?

A

DNA topoisomerase

64
Q

Difference between quinolones and fluoroquinolones?

A

Addition of fluorine improves the antibacterial activity of fluoroquinolones and helps them achieve bactericidal levels in blood and tissues

65
Q

Which fluoroquinolones is the least active against both gram + and - organisms?
a. Levofloxacin
b. Norfloxacin
c. Ciprofloxacin
d. Enoxacin

A

b. Norfloxacin

66
Q

True or false: Resistance to one fluoroquinolone, particularly if it
is of high level, generally confers cross-resistance
to all other members of this class

67
Q

The third-generation quinolones has expanded activity against ___ organisms
* Gram+ bacteria
* Gram- bacteria

A

Gram+ bacteria

68
Q

What is the mechanism of action of fluoroquinolones?
* Inhibit protein synthesis
* Inhibit folic acid synthesis
* Inhibition of cell wall synthesis
* Disruption of cell membrane structure or function
* Inhibition of nucleic acid synthesis, structure or function

A

Inhibition of nucleic acid synthesis, structure or function

iPTX III (28 decks)

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