macrolides, vanco, and metronidazole med chem/pharmacology

Question 1

coverage of macrolides

Answer 1

• strep

- Gm- bacteria

Question 2

macrolide side effects

Answer 2

GI (erythromycin most)

Question 3

macrolides MoA

Answer 3

binds 50s subunit of ribosome at E site (static)

Question 4

important part of ribosome for macrolide binding

Answer 4

Adenine 2058

*major mutation site in resistance)

Question 5

forms of resistance to macrolides

Answer 5

• mutation at A2058
• esterases
• efflux

Question 6

specific compound in erythromycin degradation responsible for GI effects

Answer 6

the spiroketal

Question 7

what makes clarithromycin and azithromycin have less GI effects

Answer 7

structures prevent the formation of the ketal

Question 8

unique side effect of clarithromycin

Answer 8

metallic taste

Question 9

clindamycin MoA

Answer 9

blocks peptidyltransferase in 50S subunit

Question 10

clindamycin coverage

Answer 10

• Gm+

- anaerobes

Question 11

side effects of clindamycin

Answer 11

• skin rash

- psedomembranous colitis from C.diff

Question 12

C.diff features

Answer 12

• Gm+ anaerobe
• produces spores that are hard to get rid of
• shed in feces and contaminates anything it touches

Question 13

antibiotics that can treat C.diff

Answer 13

• metronidazole
• PO vanco
• fidaxomicin

Question 14

Metronidazole MoA

Answer 14

generates a nitro radical and interferes with RNA and DNA

Question 15

metronidazole coverage

Answer 15

• anaerobes
• C.diff
• protozoans

Question 16

metronidazole side effects

Answer 16

• diarrhea
• dizziness
• neuropathy
• metallic taste

Question 17

DDIs with metronidazole

Answer 17

• warfarin (increased bleeding)

- alcohol (disulfiram-like reaction)

Question 18

Fidaxomicin MoA

Answer 18

binds to DNA template to inhibit RNA polymerase complex and transcription

Question 19

fidaxomicin coverage

Answer 19

• Gm+ anaerobes

- C.diff

Question 20

how are bacterial susceptibilities determined

Answer 20

calculating minimum inhibitory concentration

Question 21

how can we estimate the MIC

Answer 21

zone diameters on agar plate cultures

Question 22

what pharmacodynamic parameter best predicts vancomycin efficacy

Answer 22

AUC/MIC ratio

Question 23

minimum vanco trough concentration to avoid resistance

Answer 23

• for no MIC 10 mg/L

- for MIC of 1, 15 mg/L

Question 24

target trough concentration of AUC:MIC

Answer 24

at least 400

Question 25

recommended vanco dose for pts with normal renal function

Answer 25

15-20 mg/kg q8-12h

Question 26

when would you change from vanco to another drug

Answer 26

when MIC is >2 because AUC:MIC of >400 is not possible

Question 27

vanco loading dose in seriously ill pts.

Answer 27

25-30 mg/kg of actual body weight

Question 28

information needed to dose vanco

Answer 28

- weight/height - serum creatinine - albumin - recent urinary output - allergies