Antimicrobial Mechanisms

Question 1

First Aid Antimicrobials

In what suffix do fluoroquinolones end?

Answer 1

‘-floxacin’

(e.g. ciprofloxacin, levofloxacin)

Question 2

First Aid Antimicrobials

In what suffix do aminoglycosides end?

Answer 2

‘-mycin’

(e.g. gentamycin, tobramycin, streptomycin)

Question 3

First Aid Antimicrobials

In what suffix do macrolides end?

Answer 3

‘-mycin’

(e.g. azithromycin, clarithromycin,erythromycin)

Question 4

First Aid Antimicrobials

Identify which of the following are aminoglycosides and which are macrolides:

• Erythromycin*
• Gentamycin*
• Neomycin*
• Azithromycin*
• Tobramycin*
• Clarithromycin*
• Amikacin*

Answer 4

Identify which of the following are aminoglycosides and which are macrolides:

Erythromycin (macrolide)

(aminoglycoside) Gentamycin

(aminoglycoside) Neomycin

Azithromycin (macrolide)

(aminoglycoside) Tobramycin

Clarithromycin (macrolide)

(aminoglycoside) Amikacin

Question 5

First Aid Antimicrobials

Name three macrolides.

Answer 5

CEA

Clarithromycin

Erythromycin

Azithromycin

Question 6

First Aid Antimicrobials

What mechanism of action do penicillins use?

Answer 6

Blocks transpeptidase cross-linking of peptidoglycan;

also activates autolytic enzymes

Question 7

First Aid Antimicrobials

What is another name for penicillin-binding proteins?

Answer 7

Transpeptidases

Question 8

First Aid Antimicrobials

Penicillins are beta-lactam structural analogs of what?

Answer 8

D-Ala-D-Ala

Question 9

First Aid Antimicrobials

How is penicillin G administered?

Answer 9

IV or IM

Question 10

First Aid Antimicrobials

How is penicillin V administered?

Answer 10

Oral

Question 11

First Aid Antimicrobials

What mechanism of action do cephalosporins use?

Answer 11

Beta-lactam structure that inhibits peptidoglycan cross-linking

Question 12

First Aid Antimicrobials

What mechanism of action do carbapenems use?

Answer 12

Beta-lactam structure that inhibits peptidoglycan cross-linking

Question 13

First Aid Antimicrobials

What mechanism of action do monobactams use?

Answer 13

Beta-lactam structure that inhibits peptidoglycan cross-linking

Question 14

First Aid Antimicrobials

Name a monobactam.

Answer 14

Aztreonam

Question 15

First Aid Antimicrobials

What mechanism of action does vancomycin use?

Answer 15

Inhibits peptidoglycan synthesis

(by binding D-Ala-D-Ala precursors)

Question 16

First Aid Antimicrobials

What mechanism of action does bacitracin use?

Answer 16

Inhibits peptidoglycan synthesis

(by binding D-Ala-D-Ala precursors)

Question 17

First Aid Antimicrobials

What mechanism of action do aminoglycosides use?

Answer 17

30S inhibition

Question 18

First Aid Antimicrobials

What mechanism of action do tetracyclines use?

Answer 18

30S inhibition

Question 19

First Aid Antimicrobials

What mechanism of action does cloramphenicol use?

Answer 19

50S inhibition

Question 20

First Aid Antimicrobials

What mechanism of action do macrolides use?

Answer 20

50S inhibition

Question 21

First Aid Antimicrobials

Name some macrolides.

Answer 21

Erythromycin, clindamycin, azithromycin

Question 22

First Aid Antimicrobials

What mechanism of action does linezolid use?

Answer 22

50S inhibition

Question 23

First Aid Antimicrobials

What mnemonic is useful in describing which antibiotics are 30S inhibitors and which are 50S inhibitors?

Answer 23

“Buy AT 30, CCEL at 50.”

• (30S inhibition: aminoglycosides, tetracyclines*
• 50S inhibition: cloramphenicol, clindamycin. erythromycin, linezolid)*

Question 24

First Aid Antimicrobials

What mechanism of action do streptogramins (quinupristin, dalfopristin) use?

Answer 24

50S inhibition

Question 25

# First Aid Antimicrobials What mechanism of action do fluoroquinolones use?

Answer 25

DNA gyrase inhibition

Question 26

# First Aid Antimicrobials Ciprofloxacin and levofloxacin are what type of drug?

Answer 26

Fluoroquinolones

Question 27

# First Aid Antimicrobials What mechanism of action does linezolid use?

Answer 27

50S inhibition

Question 28

# First Aid Antimicrobials What mechanism of action do polymyxins use?

Answer 28

Disrupt gram-negative cell membranes

Question 29

# First Aid Antimicrobials What mechanism of action does daptomycin use?

Answer 29

Disrupt gram-positive cell membranes

Question 30

# First Aid Antimicrobials What mechanism of action does metronidazole use?

Answer 30

Generation of free radicals which damage the bacterial DNA

Question 31

# First Aid Antimicrobials What mechanism of action does rifampin use?

Answer 31

RNA polymerase inhibition

Question 32

# First Aid Antimicrobials What mechanism of action does trimethoprim use?

Answer 32

Dihydrofolate reductase inhibition | (reduction in folate synthesis)

Question 33

# First Aid Antimicrobials What mechanism of action do sulfonamides use?

Answer 33

Dihydropterate reductase inhibition | (reduction in folate synthesis)

Question 34

# First Aid Antimicrobials What mechanism of action does dapsone use?

Answer 34

Dihydropterate reductase inhibition | (reduction in folate synthesis)

Question 35

# First Aid Antimicrobials Name three penicillinase-sensitive penicillins.

Answer 35

Penicillin G or V Ampicillin Amoxicillin

Question 36

# First Aid Antimicrobials Name three penicillinase-resistant penicillins.

Answer 36

Oxacillin Nafcillin Dicloxacillin

Question 37

# First Aid Antimicrobials Name two antipseudomonal penicillins.

Answer 37

Ticarcillin Piperacillin

Question 38

# First Aid Antimicrobials Cefazolin is a \_\_\_\_-generation cephalosporin.

Answer 38

Cefazolin is a **_1st_** -generation cephalosporin.

Question 39

# First Aid Antimicrobials Cefoxitin is a \_\_\_\_-generation cephalosporin.

Answer 39

Cefoxitin is a **_2nd_** -generation cephalosporin.

Question 40

# First Aid Antimicrobials Ceftriaxone is a \_\_\_\_-generation cephalosporin.

Answer 40

Ceftriaxone is a **_3rd_** -generation cephalosporin.

Question 41

# First Aid Antimicrobials Cefepime is a \_\_\_\_-generation cephalosporin.

Answer 41

Cefepime is a **_4th_** -generation cephalosporin.

Question 42

# First Aid Antimicrobials Ceftaroline is a \_\_\_\_-generation cephalosporin.

Answer 42

Ceftaroline is a **_5th_** -generation cephalosporin.

Question 43

# First Aid Antimicrobials Name a few carbapenems.

Answer 43

**Imipenem** Meropenem Ertapenem Doripenem

Question 44

# First Aid Antimicrobials What are clavulinic acid, avibactam, sulbactam, and tazobactam?

Answer 44

Beta-penicillinase inhibitors

Question 45

# First Aid Antimicrobials You order amoxicillin for a patient and also want to administer a beta-lactamase inhibitor. What do you choose?

Answer 45

Amoxicillin-**Clavulanate**

Question 46

# First Aid Antimicrobials You order ceftazidime for a patient and also want to administer a beta-lactamase inhibitor. What do you choose?

Answer 46

Ceftazidime-**A****vibactam**

Question 47

# First Aid Antimicrobials You order ampicillin for a patient and also want to administer a beta-lactamase inhibitor. What do you choose?

Answer 47

Ampicillin-**Sulbactam**

Question 48

# First Aid Antimicrobials You order piperacillin for a patient and also want to administer a beta-lactamase inhibitor. What do you choose?

Answer 48

Piperacillin-**Tazobactam**

Question 49

# First Aid Antimicrobials You order imipenem for a patient. What should always be administered with imipenem?

Answer 49

**Cilastatin** (to prevent inactivation of imipenem in the renal tubules)

Question 50

# First Aid Antimicrobials What cell adaptations can cause resistance to penicillin G or penicillin V?

Answer 50

Beta-lactamases Mutations in penicillin-binding proteins

Question 51

# First Aid Antimicrobials What cell adaptations can cause resistance to cephalosporins?

Answer 51

Cephalosporinases (a type of beta-lactamase) Mutations in protein-binding proteins

Question 52

# First Aid Antimicrobials What cell adaptations can cause resistance to vancomycin?

Answer 52

Mutations of D-Ala-D-Ala to D-Ala-D-***Lac***

Question 53

# First Aid Antimicrobials What cell adaptations can cause resistance to tetracyclines?

Answer 53

Plasmid-encoded transport pumps (decreasing uptake or increasing efflux)

Question 54

# First Aid Antimicrobials What cell adaptations can cause resistance to fluoroquinolones?

Answer 54

Mutations in DNA gyrase Efflux pumps

Question 55

# First Aid Antimicrobials What cell adaptations can cause resistance to macrolides?

Answer 55

Methylation of 23S rRNA-binding site

Question 56

# First Aid Antimicrobials Which penicillins are penicillinase-sensitive?

Answer 56

The **aminopenicillins** | (ampicillin, amoxicillin)

Question 57

# First Aid Antimicrobials What is the main difference between ampicillin and amoxicillin?

Answer 57

Amoxicillin has a higher oral bioavailability