Unit 3: K43b.Beta-Lactams Flashcards

1
Q

Beta-Lactams: how they work

A
Inhibit cell (peptidoglycan) wall synthesis 
OR break apart cell wall 
BY binding to enzymes in cell membrane causing autolysis and cell death
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2
Q

Beta-Lactams: what makes something a beta-lactam?

A

The beta-lactam ring (think: chemistry)

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3
Q

Penicillins: 3 Groups

A
  1. Penicillins: great against gram+ organisms, gram- cocci, and non-beta-lactamase-producing anaerobes; little activity against gram- rods
  2. Anyistaphylococcal penicillins: resistant to beta-lactamases
  3. Extended spectrum penicillins: antibacterial spectrum of penicillins, improved activity against gram- rods, susceptible to hydrolysis by beta-lactamases
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4
Q

Peptidoglycan is a…

A

cross-linked polymer of polysaccharides and peptides

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5
Q

Cross-links give the cell wall its…

A

RIGIDITY

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6
Q

Beta-lactam antibiotics kill bacterial cells only when…

A

they are actively growing and synthesizing cell wall

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7
Q

PBP

A

Penicillin binding protein

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8
Q

MOA

A

Mechanism of action

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9
Q

MOA of Penicillins

A

PCN binds to PBP that cross link the peptidoglycan layer. The wall breaks apart, and osmotic pressure causes the bacteria to swell and then rupture/lyse

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10
Q

How do bacteria become resistant to penicillins?

A
  1. Inactivation of antibiotic by beta-lactamase (most common mechanism)
  2. Modification of target PBPs
  3. Impaired penetration of drug to target PNPs
  4. Antibiotic efflux
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11
Q

Function of peptidoglycan

A

Allows cell to withstand osmotic pressure. If peptidoglycan gets destroyed, the is most pressure overwhelms the cell.

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12
Q

How does beta-lactamase work?

A

Breaks the beta-lactam ring, which is essential to the function of beta-lactam antibiotics

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13
Q

MSSA vs MRSA

A

Methicillin SENSITIVE staph aureus

vs

Methicillin RESISTANT staph aureus

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14
Q

What is interesting about oxacillin?

A

Used to test staph aureus to see if it’s MRSA or MSSA

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15
Q

Penicillins: Side Effects

A

Serious reactions are more rare

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16
Q

Important note for penicillins and mononucleosis

A

Ampicillin and amoxicillin can be associated with skin rashes when prescribed in the setting of viral illnesses. The patient can end up with an “allergy” on their chart, eliminating beta-lactams as a class (which is a huge blow in terms of what medications they can take for infections)—when they might not even have a true allergy

17
Q

Cephalosporins: how they differ from penicillins

A

Similar, but are more stable/resistant to beta-lactamases —> broader spectrum

18
Q

How many generations of cephalosporins are there?

A

Technically 4. 5th generation ceftaroline is the only one that covers MRSA.

19
Q

Cefazolin can only be given …

20
Q

Cephalexin route is…

21
Q

Advantage of cefuroxime

A

Relatively active against organisms inhibited by 1st generation drugs, BUT ALSO has extended GRAM- coverage

22
Q

Ceftriaxone is often used for …

A

CAP (community acquired pneumonia)
OR
UTI

23
Q

Cefepime is good for _______ spectrum

OR ___________

A

Broad

pseudomonas pneumoniae

24
Q

Why is ceftaroline special?

A

1st beta-lactam that covers MRSA

25
Side effects of cephalosporins
Can cause skin rash Can irritate kidneys Granulocytopenia
26
Monitoring for cephalosporins
CBC | BMP (kidneys)
27
Can a patient with a PCN allergy take a cephalosporin?
MINOR: yes MAJOR/ANAPHYLAXIS: caution; should not receive 1st or 2nd generation cephalosporin; if cephalosporin really needed, patient may need to be hospitalized to be desensitized
28
Monobactams: a beta-lactam that DOES NOT cover _____
GRAM+ bacteria or anaerobes
29
The only monobactam available in the US
Aztreonam
30
What is special about beta-lactamase inhibitors?
By themselves, not very effective. But coupled with a penicillin, can inhibit beta-lactamase and make penicillin more effective
31
Claulvulanic acid gets added to ______ to make ________
Clavulanic acid + AMOXICILLIN = AUGMENTIN
32
Tazobactam gets added to ______ to make ________
Tazobactam + PIPERACILLIN = ZOSYN
33
Key toxicity to watch out for with vancomycin
Nephrotoxicity
34
Monitoring for daptomycin
Creatinine phosphokinase (risk of myopathy)
35
Fosfomycin is only used for _____ How many doses?
UTI 1
36
What ointment is a beta-lactam?
Bacitracin
37
Cycloserine is used primarily to treat ...
tuberculosis caused by strains of Mycobacterium tuberculosis resistant to first-line agents.
38
Dose-related adverse effects of cycloserine
serious, dose-related central nervous system toxicity with headaches, tremors, acute psychosis, and convulsions
39
List major groups of beta-lactams
Penicillins Cephalosporins Carbapenems