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PHAR152 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What are the major antibiotic categories?

A

beta-lactams (penicillin, cephalosporins, carbapenens)
macrolides and clindamycin
tetracyclines/glycylcyclines
glycopeptides
aminoglycosides
quinolones
sulfonamides and trimethoprim
metronidazole
linezolid

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2
Q

How do penicillin’s exhibit their action?

A

bind to penicillin binding protein (PBP) resulting in inhibition of peptidoglycan synthesis and activation of autolytic enzymes in cell wall

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3
Q

True or false: penicillins are bacteriostatic

A

false
they are bactericidal

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4
Q

How does resistance develop to penicillins?

A

production of beta-lactamases
lack of PBP or altered PBP
efflux of drug out of cell
failure to synthesize peptidoglycans such as mycoplasmas or metabolically inactive bacteria

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5
Q

What is the structure of penicillins?

A

6-aminopenicillanic acid (thiazolidine ring attached to beta-lactam ring)

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6
Q

What are the natural penicillins?

A

penicillin G
penicillin V

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7
Q

Which bacteria is penicillin G highly active against?

A

gram positive and spirochetes

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8
Q

Describe penicillin G.

A

highly active against gram + and spirochetes
destroyed by beta-lactamases
acid labile (not used orally)

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9
Q

What are the available forms of penicillin G?

A

aqueous Pen G
procaine Pen G (IM)
benzathine Pen G (IM)

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10
Q

What is the difference between penicillin G and penicillin V?

A

penicillin V is an oral formulation that is more acid stable

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11
Q

What are the special instructions for use of penicillin V?

A

taken on an empty stomach

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12
Q

What are the uses of the natural penicillins?

A

DOC for:
-streptococci
-pneumococci
-meningcocci
-spirochetes
-clostridia
-anaerobic gp rods
-actinomyces
-enterococci

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13
Q

Which penicillins are designed for Staph aureus?

A

cloxacillin
methicillin
flucloxacillin
dicloxacillin

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14
Q

What are the “anti-staphylococcal” penicillins relatively resistant to?

A

beta-lactmases

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15
Q

When should the pencillins such as cloxacillin or methicillin not be used?

A

should not be used for MRSA
-methicillin resistant staph aureus

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16
Q

What is the spectrum of activity for aminopenicillins?

A

active against both gp and gn
-streptococci, enterococci, neiserria, non-blp H influenzae, e.
coli, p. mirabilis, salmonella, etc

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17
Q

What can destroy the aminopenicillins?

A

beta-lactamases

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18
Q

What are the aminopenicillins? Describe each.

A

ampicillin
-IV
-more acid stable than the natural pencillins
-poor bioavailability
amoxicillin
-oral
-better absorption than ampicillin
-can be combined with clavulanic acid

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19
Q

What is clavulanic acid?

A

beta-lactamase inhibitor

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20
Q

What does beta-lactamase do?

A

opens the beta-lactam ring of penicillins and cephalosporins
no longer active

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21
Q

What are ESBLs?

A

extended spectrum beta-lactamases
-found in E.coli and Klebsiella pneumoniae

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22
Q

What is NDM BL?

A

New Delhi metallo-beta-lactamase
-found in Acteinobacter baumannii

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23
Q

What is the ureidopenicillin presented in class?

A

piperacillin

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24
Q

Which penicillin has increased activity against Pseudomonas aeruginosa?

A

piperacillin (great against gn rods)
-parenteral only

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25
Q

Which drug is piperacillin availably combined with?

A

tazobactam (beta-lactamase inhibitor)

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26
Q

Describe the pharmacokinetics of penicillins.

A

oral bioavailability varies
wide tissue distribution including CNS
most are excreted by the kidneys
short half-life
concentration independent PD
all taken on empty stomach but one
safe in pregnancy
distributed to breast milk

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27
Q

Which pencillin should be taken with food?

A

amoxicillin

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28
Q

Why are penicillins frequently dosed?

A

short half-lifes

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29
Q

What is a drug interaction that must be kept in mind with penicillins?

A

oral contraceptives
-penicillins can destroy the estrogen
-explain it to the woman

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30
Q

What are the adverse effects of penicillins?

A

allergic reactions
anaphylactic shock
serum sickness (fever, joint stiffness, rash)
skin rashes
fever, nephritis, eosinophilia
electrolyte imbalance
neutropenia, thrombocytopenia
diarrhea, GI upset (most common)

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31
Q

What is the structure of cephalosporins?

A

7-aminocephalosporanic acid

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32
Q

Why are cephamycins not considered to be a true cephalosporin?

A

they have an oxygen where the sulfur is

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33
Q

What is the MOA of cephalosporins?

A

same as penicillins (PBP to decrease peptidoglycan synthesis)
bactericidal

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34
Q

In terms of resistance, how do cephalosporins differ from penicillins?

A

cephalosporins are resistant to beta-lactamases produced by Staph aureus and common gnb (increased spectrum)

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35
Q

How does resistance develop to cephalosporins?

A

lack of PBP or altered PBP
beta-lactamase
efflux
inability to penetrate

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36
Q

What are the first generation cephalosporins?

A

oral: cephalexin and cefadroxil
IV/IM: cefazolin

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37
Q

What is the activity of first generation cephalosporins?

A

gram positive cocci, NOT enterococci or MRSA
some gram negative bacilli (E.coli, Proteus, Klebsiella)

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38
Q

True or false: first generation cephalosporins penetrate the CNS

A

false

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39
Q

What situations are first generation cephalosporins the DOC?

A

not the DOC for any infection except cefazolin for surgical prophylaxis

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40
Q

What are the second generation cephalosporins?

A

oral: cefuroxime axetil, cefprozil
IV/IM: cefuroxime

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41
Q

What is the activity of second generation cephalosporins?

A

organisms covered by 1st gen cephalosporins
greater coverage of gram negative bacilli (not Pseudomonas aeruginosa)

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42
Q

What are the third generation cephalosporins?

A

cefotaxime, ceftriaxone, ceftadizime (IV)
cefixime (oral)

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43
Q

What is ceftadizime reserved for?

A

Ps. aeruginosa

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44
Q

What is the activity of third generation antibiotics?

A

decreased activity against gram positive cocci (except Strep pneumoniae)
enhanced activity against gram negative bacilli

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45
Q

What is the difference in tissue distribution between 1st gen and 3rd gen cephalosporins?

A

3rd gen can penetrate the CNS

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46
Q

What are the fourth generation cephalosporins?

A

cefepime (enterobacter and citrobacter, Ps. aeruginosa)
ceftaroline and ceftobiprole (MRSA, ampicillin sensitvive E. faecalis, penicillin resistant S. pneumoniae)

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47
Q

What are the adverse effects of cephalosporins?

A

hypersensitivity
diarrhea and skin rash=most common
other: fever, granulocytopenia, hemolytic anemia

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48
Q

What is a unique side effect of ceftriaxone?

A

biliary pseudolithiasis

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49
Q

What are the carbapenems?

A

imipenem
meropenem
ertapenem

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50
Q

What is imipenem always given with?

A

cilastatin
-protects from dehydropeptidase and prolongs antibacterial
effects

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51
Q

What is the activity of imipenem and meropenem?

A

gram positive
gram negative (including Pseudomonas)
anaerobic organisms

52
Q

What is the activity of ertapenem?

A

poor activity against enterococcus and P. aeruginosa

53
Q

Which carbapenem is given once daily?

A

ertapenem (long half-life)

54
Q

Describe monobactams.

A

monocyclic beta-lactam ring
resistant to beta-lactamases
active against gnb including P. aeruginosa
not active against ESBL or AmpC producers

55
Q

What is a monobactam discussed in class, not available in Canada?

A

aztreonam

56
Q

What are the macrolides?

A

erythromycin
clarithromycin
azithromycin

57
Q

What is the MOA of macrolides?

A

attach to the 23S rRNA on the 50S subunit of bacterial ribosome resulting in inhibition of protein synthesis
bacteriostatic; time dependent killing (conc independent)

58
Q

How does resistance develop to macrolides?

A

methylation of the rRNA receptor
inactivating enzymes
efflux

59
Q

What is the spectrum of activity of macrolides?

A

gram positive: pneumococci, streptococci, corynbacteria
M pneumoniae
Chlamydia trachomatis
C. pneumophilia
Bordatella pertussis
Campylobacter jejuni
Helicobacter pylori

60
Q

What are the available forms of erythromycin?

A

base
stearate (succinate)
estolate

61
Q

Why is erythromycin avoided IV?

A

can cause severe phlebitis

62
Q

What are the adverse effects of erythromycin?

A

GI (macrolides known to have significant GI effects)
increased liver function tests (LFTs)
cholestatic hepatitis (increased with estolate and pregnancy)
QT prolongation/cardiac arrhythmias (especially with CYP 3A inhibitors)

63
Q

What is the activity of clarithromycin and azithromycin?

A

active against staph and strep
useful for some MRSA
enhanced activity against variety of organisms

64
Q

If an organisms is resistant to erythromycin, then which other drugs would we suspect this organism to be resistant to?

A

clarithromycin and azithromycin

65
Q

How do clarithromycin and azithromycin compare to erythromycin in dosing and adverse effects?

A

less frequent dosing
lower rate of GI effects

66
Q

What is the concern with a 5 day therapy of azithromycin?

A

azithromycin has long half-life
5 days of azithromycin=10 days of therapy
may lead to more resistance

67
Q

What are the uses of the macrolides?

A

URTIs
STIs
acne

68
Q

What are the drug interactions for macrolides?

A

erythromycin and clarithromycin are substrates+inhibitors of CYP 3A4, so many drugs that are metabolized by CYP 3A4
antiarrythmias
antidepressants
anticonvulsants
statins
fewer with azithromycin

69
Q

What is the MOA of clindamycin?

A

same as macrolides
-has different structure

70
Q

When is clindamycin the DOC?

A

never

71
Q

What is the spectrum of clindamycin?

A

anaerobes
S.aureus
some MRSA
streptococci

72
Q

When is clindamycin typically used?

A

penicillin allergy
resistant organism

73
Q

What are the adverse effects of clindamycin?

A

nausea, vomitting, diarrhea
rash
elevated LFTs
esophageal irritation
ASSOCIATED WITH C. DIFFICILE DIARRHEA

74
Q

What are the tetracyclines?

A

tetracycline
minocycline
doxycycline

75
Q

What is the MOA of tetracyclines?

A

inhibit binding of aminoacyl-tRNA to the 30S unit of ribosome therby inhibiting protein synthesis
bacteriostatic

76
Q

What is the spectrum of activity of tetracyclines?

A

many gp and gp
-high rates of resistance

77
Q

When are tetracyclines the DOC?

A

rickettsiae
bartonella
chlamydia
M. pneumoniae

78
Q

What are the adverse effects of tetracyclines?

A

GI upset
skin rashes
photosensitivity
yeast overgrowth
deposited in bones and teeth
hepatitis
vestibular toxicity (dizziness, vertigo, ataxia)

79
Q

Which group are tetracyclines contraindicated in?

A

children <8

80
Q

Which tetracycline is associated with hypersensitivity reactions?

A

minocycline

81
Q

What are some drug interactions with tetracyclines?

A

some anticonvulsants
divalent and trivalent cations reduce absorption
-iron, bismuth, calcium, magnesium, aluminum
increased INR and bleeding with warfarin

82
Q

What are the synthetic analogues of tetracyclines?

A

glycylcyclines:
-tigecycline

83
Q

What is the spectrum of activity of glycylcyclines?

A

many gp and gn
-MRSA
-S. pneumoniae
-enterococci
-salmonella
-shigella
-actinobacter
-anaerobes

84
Q

How are glycylcyclines eliminated?

A

biliary tract or feces

85
Q

What is the reserved usage of glycylcyclines?

A

resistant organisms

86
Q

What is the glycopeptides studied in class?

A

vancomycin

87
Q

What is the MOA of glycopeptides?

A

inhibits cell wall peptidoglycan synthesis
bactericidal

88
Q

Which organisms are resistant to vancomycin?

A

VRE
S. aureus

89
Q

What is the spectrum of activity of vancomycin?

A

gpc in particular enterococci
PRSP
MRSA
clostridia
some bacilli

90
Q

When is vancomycin given orally? What about IV?

A

orally: C. difficile only (not orally absorbed)
IV for serious infection

91
Q

What are the adverse reactions of vancomycin?

A

nephrotoxicity (especially in combo with nephrotoxins)
ototoxicity (hearing impairment, messes with balance)
red-man syndrome
granulocytopenia

92
Q

True or false: therapeutic drug monitoring is not commonly performed with vancomycin

A

false
commonly performed

93
Q

What are the aminoglycosides?

A

streptomycin
gentamicin
tobramycin
amikacin

94
Q

What is the MOA of aminoglycosides?

A

inhibit protein synthesis by inhibiting 30S subunit of bacterial ribosome

95
Q

How does resistance develop to aminoglycosides?

A

mutation or methylation of 16S rRNA-binding site
enzymatic destruction of drug
lack of permeability to the drug molecule
active efflux

96
Q

What is the spectrum of aminoglycosides?

A

aerobic gnb
synergistic with penicillins for enterococci and streptococci
streptomycin for TB

97
Q

What is the route of administration for aminoglycosides?

A

IV/IM (not orally absorbed)

98
Q

How good is the penetration of aminoglycosides? How are they eliminated?

A

poor tissue penetration, not CNS
renal elimination

99
Q

True or false: therapeutic drug monitoring is commonly performed with aminoglycosides

A

true

100
Q

What are the adverse effects of aminoglycosides?

A

nephrotoxicity
ototoxicity
neuromuscular blockade
allergies rare

101
Q

What are the fluoroquinolones?

A

ciprofloxacin
levofloxacin
moxifloxacin

102
Q

What is the MOA of fluoroquinolones?

A

inhibit DNA gyrase or topoisomerase II & IV
bacteriocidal

103
Q

How does resistance develop to fluoroquinolones?

A

alteration of the A or B subunit of DNA gyrase
mutation in ParC or ParE of topoisomerase IV
change in outer membrane permeability
efflux

104
Q

What is the spectrum of fluoroquinolones?

A

highly active against gnb, haemophilus, neisseriae, chlamydiae
ciprofloxacin-P.aeruginosa
levofloxacin-S.pneumoniae
moxifloxacin-anaerobes

105
Q

What are the uses of fluoroquinolones?

A

UTIs
STIs
lower respiratory tract infections
enteritis/travellers diarrhea
drug resistant mycobacterial infections

106
Q

Describe the pharmacokinetics of fluoroquinolones.

A

excellent oral bioavailability
available IV or po but parenteral use not commonly needed
ciprofloxacin and levofloxacin-renal elimination
moxifloxacin-biliary pathway

107
Q

What are the adverse effects of fluoroquinolones?

A

nausea, vomiting, diarrhea
insomnia, headache, dizziness
other CNS effects including seizures
skin rashes
impaired liver function
tendinitis/tendon rupture
prolongation of QTc interval
hypo/hyperglycemia
C. difficile
peripheral neuropathy

108
Q

What are the drug interactions associated with fluoroquinolones?

A

di and trivalent cations
QTc prolongation
CYP 1A2 inhibitors
increased INR with warfarin

109
Q

What are the reserved situations for fluoroquinolones?

A

resistant organisms or when you cant use the DOC
not used in children <18

110
Q

What is the MOA of sulfamethoxazole?

A

structural analogue of PABA; competitively inhibits dihydrofolate acid synthesis

111
Q

What is the MOA of trimethoprim?

A

binds to dihydrofolate reductase therefore inhibiting the reduction of dihydrofolic acid to tetrahydrofolic acid

112
Q

How does resistance develop to SMX and TMP?

A

ability of cell to use preformed folic acid

113
Q

What is the spectrum of SMX and TMP?

A

wide spectrum of gp, gn, chlamydiae, nocardiae, protozoa
staphylococci-including MRSA
S. pneumoniae (not group A strep)
S. maltophilia
moraxella
H. influenza
enterobacteriaciae
brucella
pneumocystis jirovecii

114
Q

What are the uses of SMX and TMP?

A

UTIs
skin and soft tissue infections-MRSA
PJP
many others

115
Q

What are the adverse effects of sulfonamides and trimethoprim?

A

skin rashes (can be severe)
hypersensitivity
headache
GI
bone marrow suppression
hyperkalemia & hyponatremia
photosensitivity

116
Q

What is CI of SMX/TMP? What is a caution with SMX/TMP?

A

CI: first and third trimester of pregnancy
caution: renal dysfunction

117
Q

What is the MOA of metronidazole?

A

unknown but possible inhibition of nucleic acid synthesis and disruption of DNA

118
Q

What is the spectrum of metronidazole?

A

anaerobes including C.difficile
protozoa-trichomonas, giardia

119
Q

Which organism is resistant to metronidazole?

A

propionibacterium

120
Q

What are the adverse effects of metronidazole?

A

GI
metallic taste
headache
dark urine
peripheral neuropathy
disulfiram-like reaction with alcohol
insomnia
stomatitis

121
Q

What are the drug interactions of metronidazole?

A

alcohol
increased INR and bleeding with warfarin

122
Q

What is the MOA of linezolid?

A

inhibits protein synthesis
usually bacteriostatic
bactericidal against Streptococci

123
Q

What is the spectrum of linezolid?

A

streptococci
enterococci (including VRE)
staphylococci (including MRSA)

124
Q

What is the reserved use of linezolid?

A

multi-drug resistant organisms
an alternative to vancomycin

125
Q

What are the adverse effects of linezolid?

A

headache
nausea, vomiting, diarrhea
rash
increased LFTs
myelosuppression
optic/peripheral neuropathy
lactic acidosis
decreased seizure threshold

126
Q

What are the drug interactions for linezolid?

A

increased serotonin syndrome risk with SSRIs and MAOs
rifampin decreases linezolid levels

PHAR152 (21 decks)

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