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Micro > 03a: Antibacterial Agents > Flashcards

03a: Antibacterial Agents Flashcards

1
Q

List the four sites of antibiotic action.

A
  1. Cell wall synthesis
  2. Protein synthesis
  3. Nucleic acid synthesis
  4. Folic acid synthesis
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2
Q

List the classes of antibiotics that target cell wall synthesis. Star the beta lactams

A
  1. Penicillins*
  2. Vancomycin
  3. Beta-Lactamase Inhibitors
  4. Cephalosporins*
  5. Carbapenems*
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3
Q

Penicillin is (bactericidal/bacteriostatic) and (time/conc)-dependent.

A

Bactericidal; time-dependent

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4
Q

Mechanism of action of beta lactams is (stim/inhib) of (X), followed by bacterial cell (Y).

A

Inhibition;
X = PBPs (cross link peptide chains of peptidoglycan)
Y = lysis (via osmotic P or autolysins)

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5
Q

Natural penicillins, such as (X), primarily target gram (pos/neg) (aerobes/anaerobes) and is treatment of choice for which situations/infections?

A

X = penicillin G
Gram-pos aerobes (strep);

  1. Strep (GAS pharyngitis)
  2. Syphilis
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6
Q

Extended spectrum penicillins differ from natural penicillins in that they have greater:

A

access/ability to penetrate through O.M. of gram negatives

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7
Q

Aminopenicillins, such as (X), have coverage similar to penicillin G with (more/less) coverage for:

A

X = ampicillin; more

  1. Enterococcus
  2. Listeria
  3. Enterobacteriaceae
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8
Q

T/F: Aminopenicillins have very broad range of coverage for gram positives.

A

False

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9
Q

T/F: Penicillinase-resistant penicillins have very broad range of coverage for gram positives.

A

True

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10
Q

Drug of choice for endocarditis prophylaxis (i.e. via enterococcus).

A

Aminopenicillins (ex: ampicillin)

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11
Q

T/F: Most penicillins must be given by IV or IM to achieve adequate levels.

A

True (degraded by gastric acid)

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12
Q

T/F: Penicillins distribute well into most tissues, particularly bone/CSF.

A

False - less so in bone/CSF, though CSF levels are 5-20% of serum levels

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13
Q

Penicillins are mainly excreted (changed/unchanged) via which route?

A

Unchanged;

Renal (rapid)

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14
Q

Most common adverse effect of penicillins.

A

Hypersensitivity (3-10%), though anaphylaxis is rare

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15
Q

T/F: There may be cross-reactivity between penicillins and cephalosporins, but not other beta-lactams.

A

False - can be cross-reactivity between any of those

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16
Q

Beta-Lactamase Inhibitor example.

A

Clavulanic acid

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17
Q

Cephalosporins have which mechanism of action?

A

They’re beta-lactams! Similar to penicillins (inhibit PBPs)

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18
Q

(X) is a first-generation cephalosporin that acts primarily on which type of bacteria?

A

X = cefazolin

Gram-positive aerobes (ex: strep, MSSA)

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19
Q

(X) is a second-generation cephalosporin that acts primarily on which type of bacteria? (Y) is also a second-gen drug, but with additional activity against (Z).

A

X = cefuroxime
Gram-pos (mainly Strep, less Staph) and Gram-neg aerobes;
Y = cefoxitin
Z = gram-neg anaerobes

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20
Q

Which cephalosporin would you likely use to treat respiratory infections and community acquired pneumonia?

A

Cefuroxime (second generation)

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21
Q

(X) is a third-generation cephalosporin that acts primarily on which type of bacteria?

A 
X = ceftriaxone
Gram pos (mainly Strep, less Staph) and gram neg aerobes (less than fourth gen)
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22
Q

Which cephalosporin would you likely use to treat strep pneumo and gram negative infections?

A

Gen 3 (ceftriaxone)

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23
Q

Which cephalosporin would you likely use to treat hospital-acquired Pseudomonas?

A

Gen 4 (cefepime)

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24
Q

T/F: Gen 4 cephalosporins have no gram-positive acitivty.

A

False - similar to Gen 1 activity

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25
Q

T/F: Cephalosporins have no activity against anaerobes.

A

False - Cefoxitin(a gen 2) does against gram-neg anaerobes

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26
Q

Aside from (X), the pharmacokinetics of cephalosporins are similar to (Y) drugs.

A 
X = ceftriaxone (longer half-life and biliary excretion)
Y = penicillins
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27
Q

T/F: Cephalosporins have adverse effects/toxicity overall similar to penicillins.

A

True

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28
Q

Carbapenems have which mechanism of action?

A

They’re beta-lactams! Similar to penicillins (inhibit PBPs)

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29
Q

Carbapenems: (X) is combined with (Y) to prevent:

A 
X = imipenem
Y = cilastatin

Imipenem brakdown to nephrotoxic product

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30
Q

List the three mechanisms that pathogens use for antimicrobial resistance.

A
  1. Efflux of drug
  2. Alteration of drug
  3. Degradation of drug
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31
Q

(X) are broad-spectrum agents, generally reserved for documented resistance activity. These agents work on gram (pos/neg) (aerobes/anaerobes).

A

X = carbapenems

Gram pos and neg aerobes and anaerobes

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32
Q

Most common adverse effect of carbapenems are:

A

GI disturbances

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33
Q

T/F: Vancomycin is a beta-lactam that’s bactericidal and time-dependent.

A

Partly false - it’s a glycopeptide (not beta-lactam)

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34
Q

Spectrum of vancomycin is gram (pos/neg) (aerobes/anaerobes).

A

Gram pos aerobes and anaerobes (including MRSA)

35
Q

Vancomycin primarily used for which two scenarios?

A
  1. MRSA

2. Pt with anaphylaxis to beta-lactams

36
Q

“Red man syndrome” can be seen with infusion of (X) drug too rapidly.

A

X = vancomycin

37
Q

List the classes of antibiotics that target protein synthesis.

A
  1. Aminoglycosides
  2. Tetracyclines
  3. Macrolides
  4. Clindamycin
38
Q

Aminoglycosides, such as (X), have which mechanism of action?

A

X = gentamicin

Bind (irreversibly) to 30S ribosome (causing misreading)

39
Q

Gentamicin activity is (bactericidal/bacteriostatic) and (time/conc)-dependent. Its spectrum of activity mainly includes gram (pos/neg) (aerobes/anaerobes).

A

Bactericidal;
Conc-dependent
Gram neg (and limited gram pos) aerobes

40
Q

Distribution of gentamicin is primarily into which body compartment?

A

Extracellular (highly polar); no CNS penetration

41
Q

Adverse effects of gentamicin.

A
  1. Nephrotoxicity (reversible)

2. Ototoxicity (auditory/vestibular; irreversible)

42
Q

Tetracyclines, such as (X), have which mechanism of action?

A

X = doxycycline

Bind (reversibly) to 30S ribosome (causing misreading)

43
Q

Doxycycline activity is (bactericidal/bacteriostatic) and (time/conc)-dependent.

A

Bacteriostatic;

Time-dependent

44
Q

Gentamicin works (intra/extra)-cellularly. It is transported via which mechanisms?

A

Intracellularly (on 30S ribosome)

  1. Porin channels (passive)
  2. Active transport (oxygen dependent)
45
Q

Gentamicin is less effective in (aerobic/anaerobic) and (acidic/basic) conditions. Why?

A

Anaerobic, acidic;

Decreased transport (which is oxygen-dependent)

46
Q

(X) drugs are often used in combo with others (in sick, high-risk patients), while waiting for tests to ID illness.

A

X = Gentamicin (aminoglycosides)

47
Q

For optimal bactericidal effects, Gentamicin must have Cmax: MIC ratio of:

A

10:1 (conc-dependent)

48
Q

Doxycycline has generally broad spectrum of gram (pos/neg) coverage, but (resistance/adverse effects) pose issues.

A

Both (pos and neg aerobes and anaerobes);

Both acquired resistance and adverse effects are problematic

49
Q

Oral absorption of doxycyline is (fair/poor) and it distributes into (most/only select) tissues. How is it eliminated?

A

Fair (but decreased by simultaneous ingestion of certain minerals);
Most;
Undergoes glucoronidation, then excreted in urine and bile

50
Q

Doxycycline is contraindcated in which patient population? Why?

A

Children under 8 due to photosensitivity (rash) and tooth/bone discoloration

51
Q

Doxycycline most common adverse effect.

A

GI disturbances

52
Q

Macrolides, such as (X), have which mechanism of action?

A

X = azithromycin

Reversibly bind 50S ribosome

53
Q

Azithromycin is (bactericidal/bacteriostatic) and (time/conc)-dependent. Its coverage is similar to that of (X) drug, but with less gram (Y) coverage.

A

Depends on dose and organism;
Time-dependent
X = penicillins
Y = anaerobic

54
Q

T/F: Azithromycin has activity against T. pallidum and chlamydia.

A

False - only chlamydia

55
Q

T/F: Azithromycin has activity against H. flu and Legionella.

A

True

56
Q

T/F: Azithromycin is used in resp tract infections, such as against mycoplasma.

A

True

57
Q

Oral absorption of azithromycin is (fair/poor) and it distributes into (most/only select) tissues. How is it eliminated?

A

Fair (some food interactions;
Most (except CSF);
Metabolized by liver; excreted in bile and urine

58
Q

Clindamycin has which mechanism of action?

A

Binds 50S ribosome and inhibits protein synthesis

59
Q

Clindamycin is (bactericidal/bacteriostatic) and covers (broad/narrow) range of gram (pos/neg) bacteria.

A

Bacteriostatic;

Broad (gram pos aerobes and anaerobes)

60
Q

Clindamycin has (fair/poor) oral absorption and distributes into (most/only select) tissues. It’s excreted (changed/unchanged) in (bile/urine).

A

Fair;
Most (except CSF);
Changed (inactivated metabolites);
Bile and urine

61
Q

Most common adverse effect of Clindamycin.

A

GI tolerability

62
Q

List the two antibacterial drug classes that act as Nucleic Acid structure inhibitors.

A
  1. Quinolones

2. Metronidazole

63
Q

Generation (1/2/3/4) of quinolones are no longer used.

A

Gen 1

64
Q

Anaerobic activity is seen in gen (1/2/3/4) quinolones.

A

Gen 4

65
Q

Quinolones have (fair/poor) oral absorption and distributes into (most/only select) tissues. It’s excreted (changed/unchanged) in (bile/urine).

A

Fair;
Most;
Unchanged in urine

66
Q

The major “hole” in cephalosporin coverage is (X) bacterial species.

A

X = ENTEROCOCCUS

67
Q

Monobactam drugs, such as (X), have similar mechanism to (Y) drugs but with gram (pos/neg) spectrum only.

A

X = aztreonam
Y = penicillins
Only gram-neg

68
Q

T/F: Patient with penicillin allergy can be given aztreonam.

A

True - it’s a monobactam

69
Q

For (X) class of drugs, think DRUG INTERACTIONS.

A

X = macrolides

70
Q

(X) class of drugs covers atypical bacteria in their spectrum.

A

X = macrolides

71
Q

Linezolid is (bactericidal/bacteriostatic) and has which mechanism of action?

A

Bacteriostatic;

Binds 50S ribisome

72
Q

Linezolid has mainly gram (pos/neg) spectrum of activity. In clinical practice, it’s primarily used against which bacteria?

A

Gram positive aerobes;

MRSA and VRE infections

73
Q

Levofloxacin is part of (X) drug class. It’s (bactericidal/bacteriostatic) and (time/conc)-dependent.

A

X = quinolones
Bactericidal;
Conc-dependent

74
Q

(X) drugs are considered the “last line of defense” in the community setting.

A

X = quinolones

75
Q

Levofloxacin mechanism of action.

A

Inhibits topoisomerases (enzymes that maintain DNA supercoiling)

76
Q

T/F: Quinolone oral bioavailability is equal to IV bioavailability.

A

Essentially true! Excellent oral absorption

77
Q

T/F: Quinolones prove ineffective in hospital-acquired infections.

A

False - cover pseudomonas and atypicals

78
Q

Metronidazole is in (X) class of drugs. It’s (bactericidal/bacteriostatic) and (time/conc)-dependent. What’s the mechanism?

A

X = nitroimidazole
Bactericidal; conc-dep
Enters cell and is reduced to cytotoxic product

79
Q

Spectrum of metronidazole is:

A

ANAEROBES

80
Q

Gold standard drug for anaerobic infections, especially gram-neg.

A

Metronidazole (used for “below diaphragm” anaerobes)

81
Q

Above diaphragm: typically gram (pos/neg) anaerobes. And below diaphragm?

A

Gram-pos above; gram-neg below

82
Q

Gold standard #2 drug for anaerobic infections, especially gram-pos.

A

Clindamycin (used for “above diaphragm” anaerobes)

83
Q

“Metallic” taste is side effect of which drug?

A

Metronidazole

Micro (16 decks)

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