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Host and Defense - Exam 1 > Exam 1 - Smith - Antimicrobials I > Flashcards

Exam 1 - Smith - Antimicrobials I Flashcards

1
Q

Name some antimicrobials that affect the cell wall synthesis in bacteria.

A

Beta lactams

  • Penicillins
  • Cephalosporins
  • Carbapenems
  • Monobactams

Vancomycin

Bacitracin

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2
Q

All beta-lactam drugs are known for 3 things. Name them.

A

Require actively proliferating microorganisms

Are INACTIVE against organisms devoid of peptidoglycans
-Viruses, mycobacteria, and fungi

Are Type II Time-Dependent - Most effective is dosed to achieve serum concentrations for at least 50% of dosing interval

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3
Q

To be effective, beta-lactams must first do what?

A

Evade bacterial defenses

Penetrate outer cell layers

Protect beta-lactam ring structure

**Bind to transpeptidase enzymes (AKA Penicillin-binding protein (PBP)

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4
Q

What is transpeptidase?

A

Penicillin binding protein

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5
Q

If a penicillin binds transpeptidase, what happens?

A

Bacterial cell wall is unable to form, and the bacteria is killed (autolyse)

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6
Q

What are 2 natural penicillins?

A

Penicillin G - this is the only naturally occurring penicillin

Penicillin V (Penicillin VK)

Great against Gram (+), except S aureus, and are very susceptible to bacterial beta-lactamases

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7
Q

What are 2 aminopenicillins (extended spectrum penicillins)?

A

Ampicillin

Amoxicillin

  • Can effect Gram (-)’s
  • Still susceptible to beta-lactamases

**These drugs are often paired with beta-lactamase inhibitors

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8
Q

What are 4 penicillinase-resistant penicillins? (Anti-staphylococcal penicillins)

A

Methicillin

Nafcillin

Oxacillin

Dicloxacicillin

**Relatively resistant to beta-lactamases

USE NAF FOR STAPH - First line treatment of choice for staphylococcal endocarditis

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9
Q

What are the 3 anti-pseudonomal penicillins to know?

A

Aztreonam

Piperacillin

Ticarcillin

*Ticarcillin and then piperacillin have the broadest spectrums of activity

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10
Q

What drug has 5 generations and what is that based on?

A

Cephalosporins

Based on their activity profile

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11
Q

What is imipenem?

A

Broadest antibacterial available - It is a CARBAPENEM

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12
Q

What is the only true naturally occurring penicillin?

A

Penicillin G

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13
Q

Pen G. Tell me about it

A

NATURAL

  • Narrow spec - good against G(+)
  • *Rapidly hydrolysis by penicillinase enzymes (beta-lactamase enzymes)
  • Administered IV or IM (intramuscularly) - Poor Oral bioavailability - stomach acids destroy the drug
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14
Q

Pen V. Tell me about it

A

Acid-stable - so can be taken orally

Similar to Pen G, but less effective

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15
Q

What is benzathine penicillin?

A

Drug of choice when prolonged, low conc req’d

Treatment for syphilis

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16
Q

Aminopenicillins are what?

A

Extended spec penicillins

  • Better Gram (-) coverage than either Pen G or Pen V
  • Extends to sensitive strains of G(-) bacteria (H. Influenzae) and enterics
  • Still sensitive to beta-lactamases
  • Used for Listeria, prophylaxis of infective endocarditis, and UTIs
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17
Q

What is usually administered with a beta-lactamase inhibitor?

A

Aminopenicillins

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18
Q

What are the 2 main aminopenicillins?

A

Ampicillin

Amoxicillin

*Amoxicillin has higher oral absorption, longer half-life, and less likely to cause adverse GI effects than ampicillin

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19
Q

Amoxicillin does what to renal tubular excretion of methotrexate?

A

Causes prolonged high serum levels of methotrexate

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20
Q

What is the drug-of-choice for standard prophylactic prevention of bacterial endocarditis when appropriate?

A

Amoxicillin

*An alternative, in case of allergy is: **Cephalexin - 1st generation cephalosporin

**IF a beta-lactam allergy: Use clindamycin, azithromycin (Z-Pak), or clarithromycin

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21
Q

Ampicillin. Tell me about it.

A

Amoxicillin is much better to use b/c the side effects and requirements are lessened

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22
Q

What is the drug of choice in patients unable to take oral penicillins?

A

Ampicillin (parenterally)

  • Ampicillin causes diarrhea - pseudomembranous colitis (C diff overgrowth), rashes, hypersensitivity rxns
  • Oral contraceptives are not as effective if ampicillin is taken, and it slows renal excretion
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23
Q

How does probenecid increase serum levels of most beta-lactam antibacterials?

A

Uric acid reducer

  • Inhibits organic anion transporters
  • Probenecid does not interact with nafcillin, oxacillin, and dicloxacillin since they are Lipophilic and undergo biliary excretion, not renal
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24
Q

What is the mnemonic to know?

A

USE NAF FOR STAPH

*Use nafcillin for S aureus infections

25
Q

What are 4 drugs to know that are penicillinase-resistant penicillins?

A

Methicillin (discontinued in US)

Nafcillin

Oxacillin

Dicloxacillin

-These are the drugs of choice against S aureus and s epidermidis that are not MRSA

26
Q

What is the drug of choice for serious S aureus infections?

A

Nafcillin

27
Q

What should you know about oxacillin and dicloxacillin?

A

Activity and beta-lactamase resistance similar to methicillin, but ACID STABLE, so orally active, and reduced risk of interstitial nephritis

28
Q

Name 3 anti-pseudo Oral penicillins.

A

Carboxypenicllins

Ureidopenicillins

Monobactams

-Used for serious bacteremia, pneumonias, burn victims, UTIs

29
Q

What are 2 carboxypenicillins to know?

A

Indanyl carbenicillin

Ticarcillin
-This is more active than indanyl carbenicllin, and is an injectable agent against G(-) bacteria, esp P aeruginosa

30
Q

What is the broadest spec of the antipseudomonal penicillins?

A

Piperacillin

31
Q

What is a great drudge to use for pts with IgE-mediated penicillin allegory?

A

Aztreonam (IV)

Can cause c diff overgrowth

32
Q

What are common side effects of penicillins?

A

Hypersensitivity
-10% of people are allergic to penicillins and these people are usually cross sensitive to all other beta-lactams, including cephalopsporins

Local effects

Lethargy, confusion

Superinfection risk

33
Q

What is pseudomembranous colitis induced diarrhea?

A

Aminopenicillins (ampicillin), piperacillin, cephalosporins, and aztreonam

34
Q

Cephalosporins have how many generations and based on what?

A

5

By antimicrobial activity

  • Resistant to many older beta-lactamases
  • Renally excreted
  • Pts with history of anaphylaxis CANNOT take this**
35
Q

_____________ have a cross allergy with penicillins of only ~5%.

A

Cephalosporins

**Pts with a history of anaphylaxis cannot take cephalosporins

36
Q

1st generation cephalosporins - what drugs and what do they do?

A

Cephalexin

Cefazolin

-Active against G(+), some G(-) - Not good against enterococci, MRSA, and S epidermidis

37
Q

2nd generation cephalosporins - what drugs and what do they do?

A

Cefaclor

Cefuroxime

Cefoxitin

-Increased activity against G(-) that’s 1st gen, but less active than the 3rd gen

38
Q

3rd generation cephalosporins - what drugs and what do they do?

A

Cefdinir

Cefotaxime

Ceftaxidime

Ceftriaxone

-Less active than 1st gen against G(+) cocci, but much more active against G(-)’s like enterobacteriaceae

39
Q

4th generation cephalosporin - what drug and what does it do used for?

A

Cefepime

-Good activity against G (+) and G (-); even more beta-lactamase resistance

40
Q

5th generation cephalosporin - what drug and what does it do?

A

Ceftaroline

-Good activity against MRSA, G (+) and G (-)

41
Q

Cephalosporins generations 1-3- as generations increase, so does what two things?

A

Gram (-) activity and beta-lactamase resistance

Also, spectrum gets broader

42
Q

What is special about 4th and 5th generation cephalosporins?

A

Good with both Grams and good resistance to beta-lactamases

*5th gen is good against MRSA

**B/c 2,3,4,5 generations are more broad spec, superinfection is a risk

43
Q

________ is used for prophylaxis prior to surgery, and its most active against S aureus and strep.

A

Cefazolin

44
Q

What is cefaclor used to treat?

A

Oral sinusitis and otitis media caused by H influenzae

45
Q

What is Cefoxitin used for?

A

Kill anaerobes and extended beta-lactamase resistance

46
Q

What is Cefuroxime used for?

A

Can cross the blood brain barrier to reach CNS

47
Q

What has the broadest spectrum of all the cephalosporins and are extremely effective against G(-) organisms?

A

3rd generation cephalosporins

-Useful for G(-) bacteremias

-Can cross the BBB

48
Q

What 3rd gen cephalosporin is active against Pseudomonas aeruginosa?

A

Ceftazidime

49
Q

What is the highest selling cephalosporin?

A

Cefdinir

50
Q

What are the 1st line treatment options for strep throat?

A

Penicillin

Amoxicillin

51
Q

What is Cefepime?

A

4th generation

  • Used for Strep and methicillin-susceptible staph and P aeruginosa
  • Poor anaerobic coverage
52
Q

What is Ceftaroline?

A

5th gen cephalosporin

  • Active against MRSA
  • Used for community-acquired (CA) pneumonia and complicated skin infections
53
Q

Go thru Cephalosporins:

1st Gen

2nd Gen

3rd Gen

4th Gen

5th Gen

A

1st - Cephalexin, Cefazolin

2nd - Cefaclor, Cefuroxime, Cefoxitin

3rd - Cefdinir, Cefotaxime, Ceftazidime, Ceftriaxone

4th - Cefepime

5th - Ceftaroline

54
Q

Tell me about Carbapenems.

A

Imipenem (Primaxin namebrand)

BROADEST SPECTRUM COVERAGE AVAILABLE TO MAN (IV or IM)

Used for multi-drug resistant organisms

55
Q

What two bugs are resistant to Carbapenems?

A

MRSA

Mycoplasma

56
Q

T/F - Carbapenems are very stable in the presence of beta-lactamases, including penicillinase and cephalosporinase that are resistant to most beta-lactam antibiotics.

A

TRUE

57
Q

What is an adverse effect of carbapenem use?

A

Renal clearance is critical - Renal insufficiencies will cause seizures

58
Q

What is Imipenem coadministered with?

A

Cilistatin

  • This protects the imipenem from being degraded by the renal enzyme dehydropeptidase 1
  • Meropenem and ertapenem are not inactivated by the renal enzyme and don’t require cilistatin
59
Q

What are the protectors that are sometimes coadministered with antibiotics?

A

Usually beta-lactamase inhibitors or help protect the drug from being degraded too quickly

Host and Defense - Exam 1 (14 decks)

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