Antibacterial Agents 2

Question 1

Bacteria have a _S ribosome made up of a _S large subunit and _S small subunit

Answer 1

70; 50; 30

Question 2

Humans have a _S ribosome made up of a _S large subunit and _S small subunit

Answer 2

80; 60; 40

Question 3

These classes affect the 30S subunit of bacterial ribosomes

Answer 3

Aminoglycosides and tetracyclines

Question 4

These classes affect the 50S subunit of bacterial ribosomes

Answer 4

Cloramphenicol, Macrolides, Lincosamides, Streptogramins, and Oxazolidinones

Question 5

Streptomycin is an example of what class?

Answer 5

Aminoglycosides

Question 6

Gentamicin is an example of what class?

Answer 6

Aminoglycosides

Question 7

Are aminoglycosides static or cidal?

Answer 7

Bactericidal, used mainly against Gram(-) rods

Question 8

Streptomycin is unique because it can also be used against what bacterial agents?

Answer 8

Mycobacteria

Question 9

What type of bacteria are intrinsically resistant to aminoglycosides?

Answer 9

anaerobes

Question 10

How do bacteria build resistance to aminoglycosides?

Answer 10

1. Enzymatic inactivation through phosphylation, adenylation, or acetylation (similar to B-lactamase)
2. Alter the target through methylation of rRNA or mutation of the ribosomal proteins
3. Alter exposure through decreased uptake and increased efflux

Question 11

Aminoglycosides are synergistic with what other class?

Answer 11

B-lactams

Question 12

B-lactams are synergistic with what other class?

Answer 12

aminoglycosides

Question 13

Are tetracyclines static or cidal?

Answer 13

Bacteriostatic for intracellular bacteria, G(+), and G(-)

Question 14

Doxycyline is an example of what class?

Answer 14

tetracyclines

Question 15

Mixing a bacteriostatic drug and a bactericidal drug will have what kind of effect?

Answer 15

Antagonistic (i.e. B-lactams only work on actively dividing cells and bacteriostatic agents prevent active division)

Question 16

How do bacteria form resistance to tetracyclines?

Answer 16

1. Alter drug exposure through >28 classes of efflux pumps

2. Alter drug target through ribosome protection proteins

Question 17

Is chloramphenicol static or cidal?

Answer 17

Bacteriostatic (but can be ‘cidal against important encapsulated organisms)

Question 18

How do bacteria form resistance to chloramphenicol?

Answer 18

They enzymatically inactivate the drug through acetyl transferases

Question 19

Are macrolides static or cidal?

Answer 19

Bacteriostatic mainly against Gram(+) with some Gram(-) exceptions

Question 20

Erythromycin is an example of what class?

Answer 20

macrolides

Question 21

Azithromycin is an example of what class?

Answer 21

macrolides

Question 22

Are lincosamides static or cidal?

Answer 22

Bacteriostatic for Gram(+) and (-)

Question 23

Lincosamides are important because they work against what kind of bacteria?

Answer 23

anaerobic

Question 24

Clindamycin is an example of what class?

Answer 24

Lincosamides

Question 25

Are streptogramins A & B static or cidal?

Answer 25

Individually they are bacteriostatic but together they are bacteriocidal

Question 26

How do bacteria show resistance to macrolides, lincosamides, and streptogramin B? (MLSB)

Answer 26

1. Cross-resistance due to similar mechanisms of action

2. Alter the drug target through methylation by erm genes

Question 27

Are oxazolidinones static or cidal?

Answer 27

Bacteriostatic against many G(+) that have expresses resistance to other antibiotics

Question 28

Linezolid is an example of what class?

Answer 28

Oxazolidinones

Question 29

How do bacteria form a resistance to oxazolidinones?

Answer 29

Alter drug target through mutations in 23S rRNA gene

Question 30

Which agents act on mycobacterial cell wall?

Answer 30

isoniazid and ethambutol

Question 31

Which class disrupts the cell membrane of Gram(+) bacteria?

Answer 31

lipopeptides

Question 32

What are the antibiotics that inhibit peptidoglycan synthesis?

Answer 32

phosphomycin, cycloserine, bacitracin, glycopeptides, and B-lactams

Question 33

What is the best class to use against anaerobic organisms?

Answer 33

lincosamides