Antibiotics II Flashcards

1
Q

vancomycin - overview

A

*complex GLYCOPEPTIDE (large)
*interferes with cell wall synthesis (not in the same way as beta lactams)
*bactericidal (less rapidly than anti-staph penicillins)

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2
Q

vancomycin - mechanism of action

A

*binds to d-alanine-d-alanine of peptide precursor
*inhibits peptidoglycan synthesis via steric hinderance

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3
Q

vancomycin - mechanism of resistance

A

change from d-alanine-d-alanine to d-alanine-d-lactate

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4
Q

vancomycin - spectrum

A

gram positive organisms (including MRSA)

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5
Q

vancomycin - important pharmacokinetic property

A

*if given orally, it does NOT get into the bloodstream
*if given IV, does not get into GI tract

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6
Q

main drug for C diff ?

A

ORAL vancomycin

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7
Q

dalbavancin

A

*complex lipoglycopeptide
*same mechanism of action as vancomycin
*LONG HALF LIFE (useful in infections of IV drug users)
*active against gram-positive bacteria

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8
Q

antibiotic classes that inhibit the ribosome

A

macrolides, aminoglycosides, clindamycin, tetracyclines

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9
Q

macrolides - mechanism of action

A

inhibits protein synthesis by binding to ribosome

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10
Q

macrolides - mechanism of resistance

A
  1. *ribosomal methylation (prevents macrolide binding)
  2. drug efflux (using protein channels to pump antibiotic out of cell)
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11
Q

examples of macrolides

A
  1. erythromycin - use for pathogens without cell walls and gram positives; gives really bad diarrhea (we don’t use anymore)
  2. azithromycin - better than erythro; common for respiratory tract infections
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12
Q

aminoglycosides - mechanism of action

A

inhibit protein synthesis by binding to ribosome

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13
Q

pharmacodynamics for aminoglycosides

A

concentration-dependent killing: Cmax / MIC ( > 5)

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14
Q

examples of aminoglycosides

A

-gentamicin
-tobramycin
-streptomycin
-amikacin

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15
Q

aminoglycosides - spectrum of activity

A

*gram negative aerobes
*synergistic with beta lactams!

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16
Q

aminoglycosides - mechanism of resistance

A

enzymatic inactivation of the drug itself (sulfation, acetylation, or phosphorylation)

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17
Q

downsides of aminoglycosides

A

*low therapeutic index (may be toxic)
*need to monitor serum levels to limit toxicity (deafness, renal failure)

18
Q

clindamycin - mechanism of action

A

inhibits protein synthesis by binding to ribosome

19
Q

clindamycin - mechanism of resistance

A

*ribosomal methylation

20
Q

clindamycin - spectrum and uses

A

*gram positive cocci (staph and strep)
**used for Group A Strep (SHUTS DOWN TOXIN PRODUCTION for necrotizing fasciitis)
*above the diaphragm anaerobes

21
Q

tetracyclines - mechanism of action

A

inhibits protein synthesis by binding to ribosome

22
Q

tetracyclines - mechanism of resistance

A

drug efflux

23
Q

tetracyclines (especially doxycycline) - spectrum and uses

A

*gram positive, some gram negative
*MYCOPLASMA, CHLAMYDIA, RICKETTSIA, malaria
*go-to for tick-borne infections

24
Q

TMP/SXT (bactram) - mechanisms of action

A

*blocks 2 consecutive steps in the biosynthesis of nucleic acids
1. PABA to folic acid
2. folic acid to folinic acid

25
Q

TMP/SXT - mechanism of resistance

A

increased production of dihydrofolate reductase (bacteria just makes a LOT more to overcome antibiotic)

26
Q

TMP/SXT - spectrum

A

broad spectrum, including MRSA
*used for pneumocystis jirovecii

27
Q

metronidazole

A

DNA strand breaking effect
*used for anaerobes BELOW the diaphragm

28
Q

fluroquinolones - mechanism of action

A

*inhibit DNA gyrase and topoisomerase (stops DNA replication)

29
Q

fluroquinolones - mechanism of resistance

A
  1. mutation of DNA gyrase/topoisomerase
  2. drug efflux
30
Q

pharmacodynamics of fluroquinolones

A

AUC/MIC > 35

31
Q

examples of fluroquinolones

A

-levofloxacin
-moxifloxacin
-ciprofloxacin

32
Q

fluroquinolones - spectrum of activity

A

*ALL have good gram NEGATIVE activity (cipro best against pseudomonas)
*ALL cover the “atypicals” (mycoplasma, chlamydia, legionella
*covers TB

33
Q

what drugs can be used for traveler’s diarrhea

A

azithromycin or ciprofloxacin

34
Q

rifampin - mechanism of action

A

inhibits DNA-dependent RNA polymerase
*penetrates biofilms well

35
Q

rifampin - mechanism of resistance

A

mutations in the DNA-dependent RNA polymerase

36
Q

something to note about rifampin

A

body fluids turn ORANGE (tears, urine)

37
Q

daptomycin - mechanism of action

A

calcium-dependent increase in membrane permeability to potassium
*a LIPOPEPTIDE

38
Q

daptomycin - spectrum

A

all gram positives, including MRSA

39
Q

linezolid - mechanism of action

A

inhibits protein synthesis at the level of ribosomal translation
*can be used for MRSA

40
Q

polymxin B - mechanism of action

A

intercalates with LPS in gram negative membrane
*we don’t use it anymore (toxic)

41
Q

fidaxomicin

A

*nonabsorbable oral drug
*useful for C diff
*VERY expensive (we should use vancomycin)
*example of a macrolide