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FOM - WLB > Week 3 Prunuske - Principles of Chemotherapy > Flashcards

Week 3 Prunuske - Principles of Chemotherapy Flashcards

1
Q

What do all beta-lactam antibiotics bind to?

A

Penicillin Binding Proteins (transpeptidases)

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2
Q

What kind of reactions do transpeptidases catalyze?

A

Terminal reactions in bacterial wall synthesis.

(connects the peptidoglycan chains together via peptide bonds)

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3
Q

What happens when transpeptidase is inhibited?

A

cell wall precursors builds up >> activates autolytic enzymes

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4
Q

What is the primary mechanism of action of Beta-lactam antibiotics?

A
  • Inhibit cross-linking of the peptidoglycan by transpeptidase
  • Weakens cell wall, cell bursts in hypotonic solution
  • Bactericidal
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5
Q

What are the main two forms of Penicillin?

A
  • Penicillin V (oral)
  • Penicillin G (IV form)

(active against Gram +)

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6
Q

What is the effect of administering Probenecid simultaneously with Penicillin?

A

decreases renal excretion >> increases time penicillin is in the blood

(impairs renal secretion of weak acids)

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7
Q

Penicillinase cleaves the beta-lactam ring and causes microbial resistance of what drugs?

A

Penicillins

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8
Q

What two drugs are Penicillinase-Resistant Penicillins?

A

Nafcillin & Dicloxacillin

(very narrow-spectrum, mainly used to treat MSSA)

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9
Q

Penicillinase inhibitors (a.k.a. beta-lactamase inhibitors) bind to what and allow penicillin to be an effective?

A

Bind irreversibly to penicillinase.

(ex. Clavulanate, Sulbactam, and Tazobactam)

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10
Q

What class of penicillins are more water soluble and can pass through porin channels?

A

Aminopenicillins

(wider spectrum, penicillinase-susceptible)

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11
Q

What are the two types of Aminopenicillins? Note: both start with “Am”

A

Ampicillin & Amoxicillin

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12
Q

What GI condition is Ampicillin associated with?

A

pseudomembranous colitis

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13
Q

Antipseudomonal penicillins are pretty broad and include what two drugs?

A

Ticarcillin & Piperacillin

(susceptible to penicillinases)

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14
Q

What drug is resistant to penicillinase and is mainly used in the treatment of MSSA?

A

Nafcillin

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15
Q

Which drug is administered if a patient is allergic to penicillin?

A

Aztreonam

(monocyclic beta-lactams, targets gm-)

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16
Q

What is the mechanism of action of Cephalosporins?

A

inhibit cell wall synthesis by binding to penicillin binding proteins (transpeptidase)

weaken cell wall > autolyse > Bactericidal

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17
Q

How are cephalosporins excreted from the body?

A

The kidney.

18
Q

What is unique about the 3rd generation of cephalosporins compared to the 1st & 2nd generations?

A

3rd generation can cross the blood brain barrier!

1st & 2nd generations cannot cross the blood brain barrier.

19
Q

What type of prophylaxis are the 1st and 2nd generation cephalosporins used for?

A

Surgical prophylaxis

20
Q

What cephalosporin drug is used to treat meningitis?

A

Ceftriaxone

21
Q

What spectrums do cephalosporins have?

A

1st generation: Gram + cocci

2nd generation: gram - > gram +

3rd generation: gram - (resistant to other Beta-lactams)

4th generation: gram +, gram - including Pseudomonas

5th generation: New (MRSA), resistance to penicillinase

22
Q

What generation of cephalosporins are strongly associated with Clostridium difficile?

A

3rd generation: Ceftriazone, cefotaxime, ceftazidime, cefdinir

23
Q

What is the mechanism of action of Carbapenems?

A

contain beta-lactam ring and bind to penicillin binding proteins

24
Q

The spectrum of carbapenems is broad, but what condition is still resistant?

A

MRSA

25
Q

Carbapenems (Imipenem/cilastatin, meropenem) are administered parenterally, meaning?

A

IV, IM, SubQ

26
Q

Why is the carbapenem Imipenem administered with cilastatin?

A

To decrease cleavage of the beta-lactam ring and to prevent the formation of potentially toxic nephrotoxic metabolite.

27
Q

What side effects are associated with carbapenems?

A

GI distress & cross allergic

*check dose with renal dysfunction to prevent seizures

28
Q

What are some symptoms associated with a penicillin allergy?

A

nausea, diarrhea, urticaria, angioedema, and anaphylaxis

Hypersensitivity (mild rash to anaphylaxis)

Seizure if CNS penetration

29
Q

What target of cell wall synthesis does Vancomycin act on?

A

Transglycosylase - prevents peptidoglycan synthesis

(bactericidal)

30
Q

What is the spectrum of Vancomycin?

A

Very narrow, only gram +

MRSA & C.diff

oral vancomycin is poorly absorbed

31
Q

What are the four mechanisms of resistance that can result in cross-resistance amongst Beta-lactams?

A
  1. Expression of beta-lactamases (penicillinases, cephalosporinases, amidases)
  2. change in the structure of Penicillin Binding Proteins
  3. Decrease in uptake of the drug (intrinsically resistant)
  4. Upregulation of efflux pumps
32
Q

What are possible side effects of Vancomycin?

A

Red man syndrome (hypersensitivity due to secretion of histamines)

Nephrotoxicity

33
Q

What reaction does Bacitracin prevent in the elongation of the peptidoglycan cell wall?

A

dephosphorylation of the bactoprenol carrier.

34
Q

What is the side of effect of Bacitracin when give IM?

A

nephrotoxicity

35
Q

Polymyxin B binds to phosphatidylethanolamine in the membrane leading to what as a result?

A

Creating holes in the membrane that leads to the release of cellular contents.

36
Q

What is the spectrum of Polymyxin B?

A

Gram - bacilli

effective against multidrug resistant microbes such as Pseudomonas and KBC

(Used in combination with other antibiotics to help facilitate entry.)

37
Q

What is the only listed side effect of Polymyxin B?

A

Nephrotoxicity

38
Q

Aggregation and depolarization of a cell occurs when Daptomycin binds to what part of the cell?

A

Cell membrane

39
Q

What difficult condition is Daptomycin used to treat?

A

MRSA + VRSA

40
Q

What types of microorganisms does Daptomycin treat?

A

Gram +

(MRSA, vanco-resistant)

41
Q

What was the only side effect of Daptomycin listed?

A

reversible organizing pneumonia binds pulmonary surfactant accumulating in pulmonary spaces

42
Q
A

FOM - WLB (20 decks)

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