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Antibiotics > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Penicillin G,V

Mechanism?

A

D-Ala-D-Ala structural analog. Bind penicillin-binding proteins (transpeptidases).
Block transpeptidase cross-linking of peptidoglycan in cell wall.
Activate autolytic enzymes.

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2
Q

Penicillin G,V

Clinical Use?

A

Mostly used for gram ⊕ organisms (S pneumoniae, S pyogenes, Actinomyces). Also used for gram ⊝
cocci (mainly N meningitidis) and spirochetes (mainly T pallidum). Bactericidal for gram ⊕ cocci,
gram ⊕ rods, gram ⊝ cocci, and spirochetes. β-lactamase sensitive.

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3
Q

Penicillin G,V

Adverse Effects

A

Hypersensitivity reactions, direct Coombs ⊕ hemolytic anemia, drug-induced interstitial nephritis.

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4
Q

Penicillin G,V

Resistance

A

β-lactamase cleaves the β-lactam ring. Mutations in PBPs.

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5
Q

Penicillinase-sensitive
penicillins

Examples?

A

Amoxicillin, ampicillin; aminopenicillins

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6
Q

Penicillinase-sensitive
penicillins

Mechanisms?

A

Same as penicillin. Wider spectrum;
penicillinase sensitive. Also combine with
clavulanic acid to protect against destruction
by β-lactamase.

AMinoPenicillins are AMPed-up penicillin.
AmOxicillin has greater Oral bioavailability
than ampicillin.

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7
Q

Penicillinase-sensitive
penicillins

Clinical Use?

A

Extended-spectrum penicillin—H influenzae,
H pylori, E coli, Listeria monocytogenes,
Proteus mirabilis, Salmonella, Shigella,
enterococci.

Coverage: ampicillin/amoxicillin HHELPSS
kill enterococci.

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8
Q

Penicillinase-sensitive
penicillins

Adverse Effects?

A

Hypersensitivity reactions, rash,

pseudomembranous colitis.

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9
Q

Penicillinase-sensitive
penicillins

Resistance?

A

Penicillinase (a type of β-lactamase) cleaves

β-lactam ring

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10
Q

Penicillinase-resistant
penicillins

Examples

A

Dicloxacillin, nafcillin, oxacillin.

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11
Q

Penicillinase-resistant
penicillins

Mechanisms

A

Same as penicillin. Narrow spectrum;
penicillinase resistant because bulky R group
blocks access of β-lactamase to β-lactam ring.

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12
Q

Penicillinase-resistant
penicillins

Clinical Use

A

S aureus (except MRSA).

“Use naf (nafcillin) for staph.”

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13
Q

Penicillinase-resistant
penicillins

Adverse Effects

A

Hypersensitivity reactions, interstitial nephritis

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14
Q

Penicillinase-resistant
penicillins

Resistance

A

MRSA has altered penicillin-binding protein

target site.

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15
Q

Antipseudomonal
penicillins

Examples?

A

Piperacillin, ticarcillin.

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16
Q

Antipseudomonal
penicillins

Mechanism?

A

Same as penicillin. Extended spectrum. Penicillinase sensitive; use with β-lactamase inhibitors.

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17
Q

Antipseudomonal
penicillins

Clinical Use?

A

Pseudomonas spp. and gram ⊝ rods.

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18
Q

Antipseudomonal
penicillins

Adverse Effects

A

Hypersensitivity reactions.

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19
Q

Cephalosporins

Mechanism

A

β-lactam drugs that inhibit cell wall synthesis
but are less susceptible to penicillinases.
Bactericidal

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20
Q

Cephalosporins

What organisms are not covered by 1st-4th generation cephalosporins?

A

Listeria, Atypicals (Chlamydia, Mycoplasma),

MRSA, and Enterococci

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21
Q

Clinical Use and examples

1st generation Cephalosporins

A

1st generation (cefazolin, cephalexin)—gram ⊕
cocci, Proteus mirabilis, E coli, Klebsiella
pneumoniae. Cefazolin used prior to surgery to
prevent S aureus wound infections.

1st generation—⊕ PEcK

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22
Q

Clinical Use and examples

2nd generation Cephalosporins

A

2nd generation (cefaclor, cefoxitin, cefuroxime,
cefotetan)—gram ⊕ cocci, H influenzae,
Enterobacter aerogenes, Neisseria spp., Serratia
marcescens, Proteus mirabilis, E coli, Klebsiella
pneumoniae.

2nd graders wear fake fox fur to tea parties.
2nd generation—⊕ HENS PEcK

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23
Q

Clinical Use and examples

3rd generation Cephalosporins

A 
3rd generation (ceftriaxone, cefotaxime, 
cefpodoxime, ceftazidime)—serious gram ⊝ 
infections resistant to other β-lactams.

Can cross blood-brain barrier.
Ceftriaxone—meningitis, gonorrhea,
disseminated Lyme disease.
Ceftazidime—Pseudomonas.

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24
Q

Clinical Use and examples

4th generation Cephalosporins

A 
4th generation (cefepime)—gram ⊝ organisms, 
with increased activity against Pseudomonas and gram 
⊕ organisms.
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25
Q

Clinical Use and examples

5th generation Cephalosporins

A

5th generation (ceftaroline)—broad gram ⊕ and
gram ⊝ organism coverage; unlike 1st–4th
generation cephalosporins, ceftaroline covers
MRSA, and Enterococcus faecalis—does not
cover Pseudomonas.

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26
Q

Cephalosporins

Adverse effects

A

Hypersensitivity reactions, autoimmune
hemolytic anemia, disulfiram-like reaction,
vitamin K deficiency. Low rate of crossreactivity even in penicillin-allergic patients.
increase nephrotoxicity of aminoglycosides.

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27
Q

Cephalosporins

Resistance mechanism?

A

Inactivated by cephalosporinases (a type of

β-lactamase). Structural change in penicillinbinding proteins (transpeptidases).

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28
Q

β-lactamase inhibitors

Examples

A

Include Clavulanic acid, Avibactam,
Sulbactam, Tazobactam. Often added to
penicillin antibiotics to protect the antibiotic
from destruction by β-lactamase.

CAST (eg, amoxicillin-clavulanate,
ceftazidime-avibactam, ampicillin-sulbactam,
piperacillin-tazobactam).

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29
Q

Carbapenems

Examples

A

Doripenem, Imipenem, Meropenem, Ertapenem (DIME antibiotics are given when there is a
10/10 [life-threatening] infection).

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30
Q

Carbapenems

Mechanism

What is Imipenem commonly prescribed along with?

A

Imipenem is a broad-spectrum, β-lactamase–
resistant carbapenem. Always administered
with cilastatin (inhibitor of renal
dehydropeptidase I) to decrease inactivation of drug
in renal tubules.

With imipenem, “the kill is lastin’ with
cilastatin.”
Newer carbapenems include ertapenem (limited
Pseudomonas coverage) and doripenem

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31
Q

Carbapenems

Clinical Use

A

Gram ⊕ cocci, gram ⊝ rods, and anaerobes.
Wide spectrum and significant side effects
limit use to life-threatening infections or
after other drugs have failed. Meropenem
has a decrease risk of seizures and is stable to
dehydropeptidase I

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32
Q

Carbapenems

Adverse effects

A

GI distress, rash, and CNS toxicity (seizures) at

high plasma levels.

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33
Q

Carbapenems

Mechanism of resistance

A

Inactivated by carbapenemases produced by,

eg, K pneumoniae, E coli, E aerogenes

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34
Q

Monobactams

Example

A

Aztreonam

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35
Q

Monobactams

Mechanism

A

Less susceptible to β-lactamases. Prevents peptidoglycan cross-linking by binding to penicillinbinding protein 3. Synergistic with aminoglycosides. No cross-allergenicit

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36
Q

Monobactams

Clinical Use

A

Gram ⊝ rods only—no activity against gram ⊕ rods or anaerobes. For penicillin-allergic patients
and those with renal insufficiency who cannot tolerate aminoglycosides

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37
Q

Monobactams

Adverse effects

A

Usually nontoxic; occasional GI upset

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38
Q

Vancomycin

Mechanism

A

Inhibits cell wall peptidoglycan formation by binding D-Ala-D-Ala portion of cell wall precursors.
Bactericidal against most bacteria (bacteriostatic against C difficile). Not susceptible to
β-lactamases.

39
Q

Vancomycin

Adverse Effect

A

Well tolerated in general but NOT trouble Free.
Nephrotoxicity, Ototoxicity, Thrombophlebitis, diffuse Flushing (red man syndrome A idiopathic
reaction largely preventable by pretreatment with antihistamines), DRESS syndrome

40
Q

Vancomycin

Clinincal Use

A

Gram ⊕ bugs only—for serious, multidrug-resistant organisms, including MRSA, S epidermidis,
sensitive Enterococcus species, and Clostridium difficile (oral dose for pseudomembranous colitis

41
Q

Vancomycin

Resistance mechanism

A

Occurs in bacteria (eg, Enterococcus) via amino acid modification of D-Ala-D-Ala to D-Ala-D-Lac.
“If you Lack a D-Ala (dollar), you can’t ride the van (vancomycin).”

42
Q

Name Protein synthesis inhibitor antibiotics?

Which are bacteriostatic and which are bactericidal?

A 
30S inhibitors
Aminoglycosides 
Tetracyclines
50S inhibitors
Chloramphenicol, Clindamycin
Erythromycin (macrolides)
Linezolid
“Buy AT 30, CCEL (sell) at 50.

All are bacteriostatic, except aminoglycosides
(bactericidal) and linezolid (variable)

43
Q

Aminoglycosides

Mechanism

A

Bactericidal; irreversible inhibition of initiation
complex through binding of the 30S subunit.
Can cause misreading of mRNA. Also block
translocation. Require O2 for uptake; therefore
ineffective against anaerobes

44
Q

Aminoglycosides

Clinical Use

A

Severe gram ⊝ rod infections. Synergistic with
β-lactam antibiotics.
Neomycin for bowel surgery.

45
Q

Aminoglycosides

Adverse Effects

A

Nephrotoxicity, Neuromuscular blockade
(absolute contraindication with myasthenia
gravis), Ototoxicity (especially with loop
diuretics), Teratogenicity.

46
Q

Aminoglycosides

Mechanism of Resistance

A

Bacterial transferase enzymes inactivate the
drug by acetylation, phosphorylation, or
adenylation.

47
Q

Aminoglycosides

Examples

A

Gentamicin, Neomycin, Amikacin,
Tobramycin, Streptomycin.
“Mean” (aminoglycoside) GNATS caNNOT
kill anaerobes

Nephrotoxicity, Neuromuscular blockade
(absolute contraindication with myasthenia
gravis), Ototoxicity (especially with loop
diuretics), Teratogenicity

48
Q

Tetracycline

Mechanism

A

Bacteriostatic; bind to 30S and prevent attachment of aminoacyl-tRNA. Limited CNS penetration.
Doxycycline is fecally eliminated and can be used in patients with renal failure. Do not take
tetracyclines with milk (Ca2+), antacids (eg, Ca2+ or Mg2+), or iron-containing preparations
because divalent cations inhibit drugs’ absorption in the gut.

49
Q

Tetracycline

Clinical Use

A

Borrelia burgdorferi, M pneumoniae. Drugs’ ability to accumulate intracellularly makes them very
effective against Rickettsia and Chlamydia. Also used to treat acne. Doxycycline effective against
community-acquired MRSA

50
Q

Tetracycline

Adverse effects

A

GI distress, discoloration of teeth and inhibition of bone growth in children, photosensitivity.
Contraindicated in pregnancy

51
Q

Tetracycline

Mechanism of Resistance

A

decrease uptake or increase efflux out of bacterial cells by plasmid-encoded transport pumps.

52
Q

Tigecycline

Mechanism

A

Tetracycline derivative. Binds to 30S, inhibiting protein synthesis. Generally bacteriostatic.

53
Q

Tigecycline

Clinical Use

A

Broad-spectrum anaerobic, gram ⊝, and gram ⊕ coverage. Multidrug-resistant organisms (MRSA,
VRE) or infections requiring deep tissue penetration

54
Q

Tigecycline

Adverse Effects

A

GI symptoms: nausea, vomiting

55
Q

Chloramphenicol

Mechanism

A

Blocks peptidyltransferase at 50S ribosomal subunit. Bacteriostatic.

56
Q

Chloramphenicol

Clinical Use

A

Meningitis (Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae) and
rickettsial diseases (eg, Rocky Mountain spotted fever [Rickettsia rickettsii]).
Limited use due to toxicity but often still used in developing countries because of low cost.

57
Q

Chloramphenicol

Adverse effects

A

Anemia (dose dependent), aplastic anemia (dose independent), gray baby syndrome (in premature
infants because they lack liver UDP-glucuronosyltransferase)

58
Q

Chloramphenicol

MECHANISM OF RESISTANCE

A

Plasmid-encoded acetyltransferase inactivates the drug

59
Q

Clindamycin

Mechanism

A

Blocks peptide transfer (translocation) at 50S

ribosomal subunit. Bacteriostatic.

60
Q

Clindamycin

Clinical Use

A

Anaerobic infections (eg, Bacteroides spp.,
Clostridium perfringens) in aspiration
pneumonia, lung abscesses, and oral
infections. Also effective against invasive
group A streptococcal infection.

Treats anaerobic infections above the diaphragm
vs metronidazole (anaerobic infections below
diaphragm)

61
Q

Clindamycin

Adverse Effects

A 
Pseudomembranous colitis (C difficile 
overgrowth), fever, diarrhea.
62
Q

Linezolid

Mechanism

A

Inhibits protein synthesis by binding to 50S subunit and preventing formation of the initiation
complex

63
Q

Linezolid

Clinical Use

A

Gram ⊕ species including MRSA and VRE.

64
Q

Linezolid

Adverse Effects

A

Bone marrow suppression (especially thrombocytopenia), peripheral neuropathy, serotonin
syndrome (due to partial MAO inhibition)

65
Q

Linezolid

Mechanism of Resistance

A

Point mutation of ribosomal RNA

66
Q

Macrolides

Examples

A

Azithromycin, clarithromycin, erythromycin

67
Q

Macrolides

Mechanism

A

Inhibit protein synthesis by blocking translocation (“macroslides”); bind to the 23S rRNA of the
50S ribosomal subunit. Bacteriostatic

68
Q

Macrolides

Clinical Use

A 
Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STIs (Chlamydia), gram ⊕ cocci 
(streptococcal infections in patients allergic to penicillin), and B pertussis.
69
Q

Macrolides

Adverse Effects

A

MACRO: Gastrointestinal Motility issues, Arrhythmia caused by prolonged QT interval, acute
Cholestatic hepatitis, Rash, eOsinophilia. Increases serum concentration of theophylline, oral
anticoagulants. Clarithromycin and erythromycin inhibit cytochrome P-450

70
Q

Macrolides

Mechanism of Resistance

A

Methylation of 23S rRNA-binding site prevents binding of drug

71
Q

Polymyxins

EXAMPLE

A

Colistin (polymyxin E), polymyxin B

72
Q

Polymyxins

Mechanism

A

Cation polypeptides that bind to phospholipids on cell membrane of gram ⊝ bacteria. Disrupt cell
membrane integrity Ž leakage of cellular components Ž cell death

73
Q

Polymyxins

Clinical Use

A

Salvage therapy for multidrug-resistant gram ⊝ bacteria (eg, P aeruginosa, E coli, K pneumoniae).
Polymyxin B is a component of a triple antibiotic ointment used for superficial skin infections.

74
Q

Polymyxins

Adverse Effects

A

Nephrotoxicity, neurotoxicity (eg, slurred speech, weakness, paresthesias), respiratory failure.

75
Q

Sulfonamide

Mechanism

A

Inhibit dihydropteroate synthase, thus inhibiting
folate synthesis. Bacteriostatic (bactericidal
when combined with trimethoprim).

76
Q

Sulfonamide

Clinical Use

A

Gram ⊕, gram ⊝, Nocardia. TMP-SMX for

simple UTI

77
Q

Sulfonamide

Adverse Effects

A

Hypersensitivity reactions, hemolysis if G6PD
deficient, nephrotoxicity (tubulointerstitial
nephritis), photosensitivity, Stevens-Johnson
syndrome, kernicterus in infants, displace
other drugs from albumin (eg, warfarin)

78
Q

Sulfonamide

Mechanism of Resistance

A 
Altered enzyme (bacterial dihydropteroate 
synthase),  uptake, or  PABA synthesis.
79
Q

Sulfonamide

Examples

A

Sulfamethoxazole (SMX), sulfisoxazole,

sulfadiazine

80
Q

Trimethoprim

Mechanism

A

Inhibits bacterial dihydrofolate reductase.

Bacteriostatic

81
Q

Trimethoprim

Clinical Use

A

Used in combination with sulfonamides
(trimethoprim-sulfamethoxazole [TMPSMX]), causing sequential block of folate
synthesis. Combination used for UTIs,
Shigella, Salmonella, Pneumocystis jirovecii
pneumonia treatment and prophylaxis,
toxoplasmosis prophylaxis.

82
Q

Trimethoprim

Adverse Effects

A

Hyperkalemia (high doses), megaloblastic
anemia, leukopenia, granulocytopenia, which
may be avoided with coadministration of
leucovorin (folinic acid).

TMP Treats Bone Marrow
Poorly.

83
Q

Fluroquinolones

Examples

A

Ciprofloxacin, enoxacin, norfloxacin, ofloxacin; respiratory fluoroquinolones—gemifloxacin,
levofloxacin, moxifloxacin.

84
Q

Fluroquinolones

Mechanism

A

Inhibit prokaryotic enzymes topoisomerase
II (DNA gyrase) and topoisomerase IV.
Bactericidal. Must not be taken with antacids

85
Q

Fluroquinolones

Clinical Use

A

Gram ⊝ rods of urinary and GI tracts (including
Pseudomonas), some gram ⊕ organisms, otitis
externa.

86
Q

Fluroquinolones

Adverse Effects

A

GI upset, superinfections, skin rashes,
headache, dizziness. Less commonly, can
cause leg cramps and myalgias.
Contraindicated in pregnant women, nursing
mothers, and children < 18 years old due
to possible damage to cartilage. Some may
prolong QT interval.
May cause tendonitis or tendon rupture in
people > 60 years old and in patients taking
prednisone. Ciprofloxacin inhibits cytochrome
P-450.

Fluoroquinolones hurt attachments to your
bones

87
Q

Fluroquinolones

Mechanism of Resistance

A

Chromosome-encoded mutation in DNA
gyrase, plasmid-mediated resistance, efflux
pumps

88
Q

Daptomycin

Mechanism

A

Lipopeptide that disrupts cell membranes of
gram ⊕ cocci by creating transmembrane
channels.

89
Q

Daptomycin

Clinical Use

A

S aureus skin infections (especially MRSA),
bacteremia, endocarditis, VRE.

Not used for pneumonia (avidly binds to and is
inactivated by surfactant). “Daptomyskin” is
used for skin infections

90
Q

Daptomycin

Adverse effects

A

Myopathy, rhabdomyolysis.

91
Q

Metronidazole

Mechanism

A

Forms toxic free radical metabolites in the
bacterial cell that damage DNA. Bactericidal,
antiprotozoal.

92
Q

Metronidazole

Clinical Use

A

Treats Giardia, Entamoeba, Trichomonas,
Gardnerella vaginalis, Anaerobes (Bacteroides,
C difficile). Can be used in place of amoxicillin
in H pylori “triple therapy” in case of penicillin
allergy.

GET GAP on the Metro with metronidazole!

Treats anaerobic infection below the diaphragm
vs clindamycin (anaerobic infections above
diaphragm)

93
Q

Metronidazole

Adverse Effects

A

Disulfiram-like reaction (severe flushing,
tachycardia, hypotension) with alcohol;
headache, metallic taste.

Antibiotics (1 decks)

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