Unit 3: K43b.Beta-Lactams

Question 1

Beta-Lactams: how they work

Answer 1

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

Question 2

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

Answer 2

The beta-lactam ring (think: chemistry)

Question 3

Penicillins: 3 Groups

Answer 3

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

Question 4

Peptidoglycan is a…

Answer 4

cross-linked polymer of polysaccharides and peptides

Question 5

Cross-links give the cell wall its…

Answer 5

RIGIDITY

Question 6

Beta-lactam antibiotics kill bacterial cells only when…

Answer 6

they are actively growing and synthesizing cell wall

Question 7

PBP

Answer 7

Penicillin binding protein

Question 8

MOA

Answer 8

Mechanism of action

Question 9

MOA of Penicillins

Answer 9

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

Question 10

How do bacteria become resistant to penicillins?

Answer 10

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

Question 11

Function of peptidoglycan

Answer 11

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

Question 12

How does beta-lactamase work?

Answer 12

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

Question 13

MSSA vs MRSA

Answer 13

Methicillin SENSITIVE staph aureus

vs

Methicillin RESISTANT staph aureus

Question 14

What is interesting about oxacillin?

Answer 14

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

Question 15

Penicillins: Side Effects

Answer 15

Serious reactions are more rare

Question 16

Important note for penicillins and mononucleosis

Answer 16

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

Question 17

Cephalosporins: how they differ from penicillins

Answer 17

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

Question 18

How many generations of cephalosporins are there?

Answer 18

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

Question 19

Cefazolin can only be given …

Answer 19

IV

Question 20

Cephalexin route is…

Answer 20

PO

Question 21

Advantage of cefuroxime

Answer 21

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

Question 22

Ceftriaxone is often used for …

Answer 22

CAP (community acquired pneumonia)
OR
UTI

Question 23

Cefepime is good for _______ spectrum

OR ___________

Answer 23

Broad

pseudomonas pneumoniae

Question 24

Why is ceftaroline special?

Answer 24

1st beta-lactam that covers MRSA

Question 25

Side effects of cephalosporins

Answer 25

Can cause skin rash
Can irritate kidneys
Granulocytopenia

Question 26

Monitoring for cephalosporins

Answer 26

CBC

BMP (kidneys)

Question 27

Can a patient with a PCN allergy take a cephalosporin?

Answer 27

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

Question 28

Monobactams: a beta-lactam that DOES NOT cover _____

Answer 28

GRAM+ bacteria or anaerobes

Question 29

The only monobactam available in the US

Answer 29

Aztreonam

Question 30

What is special about beta-lactamase inhibitors?

Answer 30

By themselves, not very effective. But coupled with a penicillin, can inhibit beta-lactamase and make penicillin more effective

Question 31

Claulvulanic acid gets added to ______ to make ________

Answer 31

Clavulanic acid + AMOXICILLIN = AUGMENTIN

Question 32

Tazobactam gets added to ______ to make ________

Answer 32

Tazobactam + PIPERACILLIN = ZOSYN

Question 33

Key toxicity to watch out for with vancomycin

Answer 33

Nephrotoxicity

Question 34

Monitoring for daptomycin

Answer 34

Creatinine phosphokinase (risk of myopathy)

Question 35

Fosfomycin is only used for _____

How many doses?

Answer 35

UTI

1

Question 36

What ointment is a beta-lactam?

Answer 36

Bacitracin

Question 37

Cycloserine is used primarily to treat …

Answer 37

tuberculosis caused by strains of Mycobacterium tuberculosis resistant to first-line agents.

Question 38

Dose-related adverse effects of cycloserine

Answer 38

serious, dose-related central nervous system toxicity with headaches, tremors, acute psychosis, and convulsions

Question 39

List major groups of beta-lactams

Answer 39

Penicillins
Cephalosporins
Carbapenems