Antimicrobials

Question 1

What is the MOA of Daptomycin?

Answer 1

Daptomycin is a cyclic lipopeptide that depolarizes the bacterial cell membrane

Question 2

Are there any mechanisms of resistance to daptomycin?

Answer 2

None as of yet!

Question 3

What happens when you give daptomycin orally?

Answer 3

Trick question!! daptomycin is only given IV once daily. Do administer after hemodialysis

Question 4

What is unique about the metabolism and elimination of Daptomycin?

Answer 4

It is 90% bound to serum albumin

and is eliminated by the kidney

Question 5

What ADEs are associated with daptomycin?

Answer 5

Muscle pain and weakness
(monitor serum creatinine kinase)
(Dapto Destroys Delts)

Question 6

Are there any drugs that should be used cautiously with daptomycin?

Answer 6

Yes use caution when co-administering with statins.

Question 7

What are the clinical uses for daptomycin?

Answer 7

1. Aerobic Gram+ (MRSA, VRSA)
2. Complicated skin and soft tissue infections
3. MSSA and MRSA bacteremia

Question 8

Why can’t daptomycin be used for pneumonia?

Answer 8

Because surfactant antagonizes daptomycin.

Question 9

What is the MOA of Linezolid?

Answer 9

binds to 23S part of the 50S ribosomal subunit and inhibits protein synthesis.

Question 10

Is Linezolid bacteriostatic or bactericidal?

Answer 10

Linezolid is bacteriostatic against Staph and Enterococci but bactericial against strep

Question 11

How is resistance to Linzolid most likely to develop?

Answer 11

Mutation of 23S portion of the bacterial ribosome

Question 12

What are the clinical uses for Linezolid?

Answer 12

MRSA
Resistant S. epidermidis
Enterococci (Especially VRE)

Basically save this one for the really bad drug resistant bugs.

Question 13

How is Linezolid eliminated?

Answer 13

Linezolid is eliminated by both renal and non-renal mechanisms.

Question 14

What are the ADEs associated with Linezolid?

Answer 14

Most common: Headache, N/V, diarrhea

Strange, Rare, and likely to be on exam: Optic/peripheral neuropathy, lactic acidosis. Myelosuppression!! –> anemia, neutropenia, etc..

Question 15

What drugs interactions should you watch out for with Linezolid?

Answer 15

Other drugs metabolized by MAO:
pseudoephedrine
phenylpropanolamine
SSRIs

(beware tyramine in diet)

Question 16

What is the MOA of Rifampin?

Answer 16

Rifampin inhibits bacterial RNA polymerase

Question 17

What are the therapeutic uses for Rifampin?

Answer 17

1. first line therapy for TB
2. MRSA and resistant S. epidermidis
3. Meningicoccal or H.flu meningitis
4. Leprosy

Question 18

What is the MOA of Clindamycin?

Answer 18

Binds to 50S subunit of ribosome and inhibits protein synthesis

Question 19

Which other antibiotic is most similar to clindamycin?

Answer 19

clindamycin is very similar to erythromycin in site of action therefore do not co-administer

Question 20

What is the spectrum of action for Clindamycin?

Answer 20

1. Effective against anaerobes of both gram stains

Just FYI:
 Peptostreptococci, actinomyces	
  –  Bacteroides	fragilis, Gram positivecocci	
  –  MRSA	
  –  Group	A Strep	
 

Question 21

What special places will clindamycin distribute to?

Answer 21

1. penetrates bone and abcesses

2. Will cross the placenta and into breast milk

Question 22

T or F: Clindamycin is used to treat meningitis?

Answer 22

F: because clindamycin does not penetrate the blood brain barrier. also does not penetrate into cells

Question 23

How is clindamycin metabolized and eliminated?

Answer 23

clindamycin is metabolized in the liver to innactive forms and it is excreted in both the urine and bile.

Question 24

What ADEs are associated with clindamycin?

Answer 24

1. Pseudomembranous colitis (could be severe)(from C. difficile treat with vanc or metronidazole)
2. Gi
3. Hypersensitvity

Question 25

What unique conditions can clindamycin treat?

Answer 25

1. Bacteroides fragilis (outside CNS) 2. Toxoplasmosis when given with pyrimethamine 3. Pneumocystis when given with primaquine

Question 26

What is the MOA of mupirocin?

Answer 26

binds to and inhibits tRNA synthetase

Question 27

For what general class of organisms is mupirocin useful against?

Answer 27

Gram+ bacteria staph, strep, MRSA

Question 28

How is mupirocin administered?

Answer 28

topically

Question 29

What are the clinical uses for mupirocin?

Answer 29

1. Impetigo | 2. elimination of MRSA carriage

Question 30

What is the MOA of bacitracin?

Answer 30

Bacitracin inhibits bacterial cell wall synthesis | prevents movement of peptidoglycan building blocks to outside the cell membrane.

Question 31

What is the most important ADE of bacitracin?

Answer 31

Severe nephrotoxicity with parenteral use. | typically given topically

Question 32

Should penicillin be taken with food?

Answer 32

Usually not

Question 33

How is penicillin eliminated?

Answer 33

metabolized in the liver and excreted by the kidney

Question 34

What are the most important ADEs to remember when prescribing penicillin?

Answer 34

hypersensitivity | possible neurotoxicity

Question 35

What is the clinical utility for penicillin?

Answer 35

Many gram+ and gram- organisms

Question 36

What is the MOA of vancomycin?

Answer 36

binds to D-Ala-D-Ala on cell wall to block polymerization of peptidoglycan.

Question 37

What is the MOA of trimethoprim sulfamethoxazole?

Answer 37

1 part trimethoprim: dihydrofolate reductase inhibition. 5 parts sulfamethoxazole: dihydropteroate synthase inhibition

Question 38

What ADEs are associated with Trimethoprim-Sulfamethoxazole?

Answer 38

Hematologic problems (give folate) drug induced fever rash diarrhea.