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antibiotics Flashcards

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1
Q

what happens if you give chloramphenicol first and penicillin second?

A

chloramphenicol is bacteriostatic, so penicillin won’t have an effect.

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2
Q

name the general cell wall inhibitors

A
  • beta lactams
  • bacitracin
  • glycopeptides
  • “others” (cycloserine and those against mycobacteria)
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3
Q

which antibiotic type inhibits transpeptidation AND actives autolysins in the cell wall?

A

beta lactams

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4
Q

how do bacteria outsmart beta-lactams?

A
  • become resistant by making beta lactamases
  • lose their PBPs
  • mutate their autolysins
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5
Q

how can we outsmart the bacteria that outsmart the beta lactams?

A

-give beta lactam antibiotics with beta lactamase inhibitors!

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6
Q

name some beta lactamase inhibitors

A
  • clavulinic acid
  • sulbactam
  • tazobactam
  • augmentin
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7
Q

what is augmentin, really?

A

amoxicillin and clavulinic acid!

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8
Q

what are the 4 major classes of beta lactams?

A
  • penicillins
  • cephalosporins
  • monobactams
  • carbapenems
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9
Q

natural penicillins (pen G and pen V) are best against what kind of bugs?

A

gram positive bacteria

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10
Q

which penicillins are beta lactamase resistant, but they have a lower activity?

A

nafcillin, oxacillin, cloxacillin

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11
Q

which penicillins are expanded spectrum antibiotics?

A

ampicillin, piperacillin, mezlocillin, ticarcillin

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12
Q

which penicillin is best used against pseudomonas?

A

ticarcillin

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13
Q

which penicillins are acid resistant and thus can be given orally?

A

amoxycillin, pen V, oxacillin

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14
Q

compare the effectiveness of penicillins and cephalosporins?

A

cephalosporins are less sensitive to beta-lactamases

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15
Q

1st generation cephalosporins?

A

not used anymore, so I won’t ask you to name them.

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16
Q

what are 2nd gen cephalosporins used against?

A

bacteroides

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17
Q

name some of those 2nd gen cephalosporins

A

-cefaclor, cefuroxime, cefoxitin

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18
Q

what are 3rd gen cephalosporins used against?

A

pseudomonas

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19
Q

what’s special about the 3rd gen cephalosporins?

A

they can penetrate BBB, so useful against bacterial meningitis

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20
Q

which ones are the 3rd gen cephalosporins?

A

ceftazidime, cephataxime, cephtriaxone, cefdinir

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21
Q

4th gen cephalosporins: used against?

A

not stated in notes, but this class is the broadest of the 5 generations of cephalosporins

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22
Q

4th gen cephalosporins?

A

cefepime

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23
Q

what do 5th gen cephalosporins fight?

A

MRSA and drug resistant pseudomonas, but not regular pseudomonas

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24
Q

which is the 5th gen cephalosporin?

A

ceftaroline

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25
Q

what’s special about the monobactam antibiotics?

A

they are resistant to beta-lactamases because of their monocyclic beta lactam structure

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26
Q

which bugs do the monobactam antibiotics work against?

A

gram negative only

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27
Q

what’s an example of a monobactam antibiotic?

A

aztreonam

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28
Q

what are carbapenem antibiotics used for?

A

broad spectrum, but it’s toxic to human cells

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29
Q

what are some carbapenems?

A

imipenem, ertapenem, meropenem

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30
Q

what are the side effects of beta lactam antibiotics?

A

allergies and toxicity

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31
Q

which beta lactams are likely to cause allergies?

A

1st: penicillin, then cephalosporins, then monobactams

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32
Q

which beta lactams are likely to cause toxicity?

A

1st: carbapenems, then cephalosporins, then penicillins, then monobactams

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33
Q

how does a carbapenem toxicity present?

A

seizures

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34
Q

how does a cephalosporin toxicity present?

A

thrombophlebitis

if in cavernous sinus, it would be a 3rd gen because it crosses BBB

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35
Q

how do bacitracins work?

A

block dephosphorylation of bactoprenol

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36
Q

what are the best uses for bacitracin?

A

topical against gram positive (typically used with other antibiotics)

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37
Q

why would we not use bacitracins in some cases?

A

it’s poorly absorbed and it causes renal toxicity (!!)

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38
Q

how go glycopeptide antibiotics work?

A
  • binds to end of AA side chain
  • blocks transglycosylation
  • blocks transpeptidation
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39
Q

can you name some glycopeptide antibiotics?

A

vancomycin & telavancin

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40
Q

how do some pesky bacteria outsmart the glycopeptides?

A
  • use an -ala-lactate instead of -ala-ala end of pentapeptide side chain
  • chromosomal vanB resistant gene
  • plasmid vanA resistant gene
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41
Q

what are glycopeptides used for?

A

NOT gram negatives; staphylococci and enterococci

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42
Q

you have an intestinal gram positive infection. what kind of antibiotic can you use?

A

oral dose of glycopeptides

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43
Q

how can we outsmart the bacteria that are vancomycin resistant?

A

doing a little organic chemistry sorcery by making an amidine in the vancomycin

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44
Q

describe the cycloserine antibiotics

A

D-ala analog

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45
Q

how does cycloserine work?

A

inhibits alanine racemase

46
Q

why would we be careful with cycloserine?

A

it’s neurotoxic

47
Q

what is cycloserine used for?

A

UTI (sometimes) and it’s the 2nd best drug for TB

48
Q

which drugs are best for mycobacteria?

A
  • isoniazid
  • ethionamide
  • ethambutol
  • pyrazinamide
  • rifampicin
49
Q

how do isoniazid and ethionamide work?

A

inhibit pyridoxine step in mycolic acid synthesis

50
Q

how does ethambutol work?

A

inhibits arabinogalactan synthesis

51
Q

what should we keep in mind about ethambutol?

A

its highly resistant, so other antibiotics are needed

52
Q

how does pyrazinamide work?

A

activated by mycobacteria enzyme; inhibits translation in a pathway that’s needed to restart stalled ribosomes during stress response

53
Q

now, name some cell membrane disruptors?

A
  • polymyxins

- daptomycin

54
Q

what’s a good example of a polymyxin?

A

colistin

55
Q

how does colistin work?

A

dissolves phosphatidylethanolamine (special phosolipid in gram negative and human membranes)

56
Q

what do we use colistin for?

A
  • topical, used with bacitracin

- last resort for resistant bugs

57
Q

why is colistin used topically?

A

ITS TOXIC.

58
Q

what’s a good example of daptomycin?

A

cubicin

59
Q

what does cubicin look like?

A

cyclic lipopeptide

60
Q

how does cubicin work?

A

dissolves in membrane and disrupts membrane potential (PMF)

61
Q

which bugs do we use cubicin for?

A

gram positive cocci, including MRSA.

62
Q

how is cubicin given?

A

IV; use with beta lactams

63
Q

which drugs are antimetabolites?

A

sulfonamides, trimethoprim

64
Q

how do antimetabolites work?

A

inhibit steps in this pathway:

PABA -> DHF –> THF –> pyrimidines

65
Q

how can bacteria outsmart the antimetabolites?

A

overproduce PABA, and alter their enzymes

66
Q

what do we use antimetabolites for?

A
  • nocardia
  • UTI
  • salmonella
  • shigella
67
Q

four classes of nucleic acid inhibitors?

A
  • fluoroquinolones
  • fidaxomycin
  • rifamycin
  • metronidazole
68
Q

name some fluoroquinolones?

A

ciprofloxacin, moxifloxacin

69
Q

how do fluoroquinolones work?

A

inhibits DNA gyrase

70
Q

how do bacteria outsmart fluoroquinolones?

A
  • alter DNA gyrase (duh)

- drug exclusion (? not so duh…)

71
Q

what bugs are fluoroquinolones usesful against?

A
  • UTI bugs
  • gram negative & positive infections
  • 2nd line against mycobacteria
  • pseudomonas
72
Q

why would we reconsider using fluoroquinolones in some patients?

A

these drugs are associated with prolonged QT interval (EKG)

73
Q

example of a fidaxomycin?

A

dificid

74
Q

how does dificid work?

A

targets switch region of RNAP and prevents RNAPs interaction with DNA (whatever that means…)

75
Q

what do we use dificid for?

A
  • C. diff colitis

- vancomycin resistant c. diff

76
Q

name some rifamycins

A

-rifampin, rifabutin, rifaximin

77
Q

how do rifamycins work?

A

block RNA polymerase elongation subunit

78
Q

how do bacteria outsmart the rifamycins?

A

alter RNA polymerase B subunit

79
Q

what do we use rifamycins for?

A
  • w/ isoniazid for mycobacteria (delays resistance)
  • meningitis (crosses BBB)
  • poxviruses
80
Q

are there any side effects of rifamycins?

A

yep. its orange when excreted in sweat and urine

81
Q

how do metronidazoles work?

A

it’s partially reduced complex with ferredoxin interacts with DNA —> breaks DNA strands —> free radicals

82
Q

what do we use metronidazoles for?

A
  • giardia (antiprotozoal)

- anaerobic bacteria like bacteriodes and clostridium

83
Q

what are the 5 main classes of protein synthesis inhibitors?

A
  • aminoglycosides
  • tetracylclines
  • chloramphenicol
  • macrolides
  • lincosamides
84
Q

name some aminoglycosides

A

streptomycin, neomycin, gentamycin, tobramycin, amikacin

85
Q

how do aminoglycosides work?

A

bind to 30s ribosome and blocks initiation by preventing attachment of tRNA-fMet

86
Q

how do bacteria outsmart the aminoglycosides?

A
  • altered P12 ribosomal protein
  • aminoglycosidases
  • altered permeability
87
Q

what do we use aminoglycosides on?

A

gram negative enteric bacteria

88
Q

which other antibiotics facilitate the entry of aminoglycosides?

A

cephalosporins and penicillins

89
Q

name some tetracyclines?

A

doxycycline, tigecycline

90
Q

how do tetracyclines work?

A

inhibits binding of aa-tRNA to A site of 30s subunit

91
Q

how do bacteria outsmart tetracyclines

A

by using efflux pumps

92
Q

what do we use tetracyclines for?

A

rickettsia, chlamydia, and mycoplasmas

93
Q

why might we not give tetracyclines to some patients?

A
  • it’s toxic
  • causes dizziness, tinnitus
  • makes teeth fluorescent
  • possible bone damage in newborns
  • crosses blood-placenta barrier (pregnancy class D)
94
Q

how do chloramphenicol drugs work?

A

inhibit peptidyl transferase rxn on 50s subunit

95
Q

what do bacteria use to outsmart chloramphenicol?

A

chloramphenicol acetyl transferase (CAT)

96
Q

what should be noted about chloramphenicol?

A
  • no longer used….

- resistant and toxic

97
Q

name some macrolides

A

erythromycin, clarithryomycin, azithromycin

98
Q

how do macrolides work?

A

bind to rRNA and inhibit translocation on 50s subunit

99
Q

how do bacteria outsmart macrolides?

A

methylate their rRNA

100
Q

what bugs do we use macrolides for?

A

gram positive and SOME gram negative

101
Q

why would we reconsider using macrolides in some patients?

A

associated with prolonged QT interval on EKG and it has increased risk of cardiovascular death (!!)

102
Q

example of a lincosamide?

A

clindamycin

103
Q

how does clindamycin work?

A

same as macrolides

104
Q

what do we use clidamycin for?

A

anaerobes (bacteroides) and malaria

105
Q

what should we note about clidamycin use?

A
  • does not cross BBB
  • long term use linked with c. diff colonization
  • one time use disrupts native flora
106
Q

tell me about nitrofurantoin

A
  • inhibits 30s

- used for UTI

107
Q

what about mupirosin?

A
  • inhibits ile-tRNA synthase

- used topically for gram +

108
Q

what’s the deal with streptogramins?

A
  • synercid= quinupristin + dalfopristin
  • inhibits 50s
  • used for VRE and VRSA (….?)
109
Q

how about oxazolidinones?

A
  • inhibits 50s

- used for VRE, MRSA

110
Q

lastly… what’s up with methenamine?

A

releases formaldehyde in acidified urine… used for UTI

111
Q

just kidding. what do C10 and BF8 do?

A

wake up persister cells from dormancy and make them sensitive to antibiotics again!

Microbiology (3 decks)

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